diff --git a/apps/edr-payment-api/src/modules/cbe-bill/bill-resolver.service.ts b/apps/edr-payment-api/src/modules/cbe-bill/bill-resolver.service.ts
index f46571c6b..342fee04a 100644
--- a/apps/edr-payment-api/src/modules/cbe-bill/bill-resolver.service.ts
+++ b/apps/edr-payment-api/src/modules/cbe-bill/bill-resolver.service.ts
@@ -48,35 +48,23 @@ export function defaultPaymentReason(
     : "Freight invoice";
 }
 
-/**
- * CBE reads Response_Description back to the payer at the counter or in the USSD prompt, so it
- * has to name the thing they are actually holding — a passenger booking or a freight invoice —
- * rather than our internal "bill" abstraction (plan §6.6).
- */
-function subjectOf(referenceType: PaymentReferenceType): string {
-  return referenceType === PaymentReferenceType.BOOKING ? "booking" : "invoice";
-}
-
-export function reasonToDescription(
-  reason: string | null | undefined,
-  referenceType: PaymentReferenceType,
-): string {
-  const subject = subjectOf(referenceType);
+/** Short descriptions per CBE integration request — CBE's channel renders them as-is. */
+export function reasonToDescription(reason: string | null | undefined): string {
   switch (reason) {
     case "ALREADY_PAID":
-      return `This ${subject} has already been paid.`;
+      return "Already paid";
     case "CANCELLED":
-      return `This ${subject} has been cancelled.`;
+      return "Cancelled";
     case "REFUNDED":
-      return `This ${subject} has been refunded.`;
+      return "Refunded";
     case "EXPIRED":
-      return `This ${subject} has expired and can no longer be paid.`;
+      return "Expired";
     // A bill reference we issued whose order has since vanished from the domain app. Same
     // wording as an unknown Bill_Id — from the teller's side it is the same situation.
     case "NOT_FOUND":
-      return "Bill not found.";
+      return "Bill not found";
     default:
-      return `This ${subject} is no longer payable.`;
+      return "Not payable";
   }
 }
 
@@ -135,7 +123,7 @@ export class BillResolverService {
         }`,
       );
       // TRANSIENT so CBE may retry the same End_To_End_Txn_Id once we recover (plan R5).
-      throw new CbeBillError("Service temporarily unavailable.", "TRANSIENT");
+      throw new CbeBillError("Service unavailable", "TRANSIENT");
     }
   }
 }
diff --git a/apps/edr-payment-api/src/modules/cbe-bill/cbe-bill.service.ts b/apps/edr-payment-api/src/modules/cbe-bill/cbe-bill.service.ts
index c56622da0..8a915ece7 100644
--- a/apps/edr-payment-api/src/modules/cbe-bill/cbe-bill.service.ts
+++ b/apps/edr-payment-api/src/modules/cbe-bill/cbe-bill.service.ts
@@ -130,7 +130,7 @@ export class CbeBillService {
       const billQuery = await this.billResolver.billQuery(intent);
       if (!billQuery.stillPayable) {
         throw new CbeBillError(
-          reasonToDescription(billQuery.reason, intent.referenceType),
+          reasonToDescription(billQuery.reason),
           "BUSINESS",
         );
       }
@@ -197,14 +197,14 @@ export class CbeBillService {
         ) {
           return mapPaymentFailure(
             dto,
-            `End_To_End_Txn_Id ${dto.End_To_End_Txn_Id} was already used by a different payment.`,
+            "Duplicate End_To_End_Txn_Id",
           );
         }
         // Replay the stored body verbatim. Never re-settle.
         return prior.responsePayload as unknown as CbePaymentResponseDto;
       }
       if (prior.tradeStatus === "PENDING") {
-        return mapPaymentFailure(dto, "Payment is being processed.");
+        return mapPaymentFailure(dto, "Payment in progress");
       }
       if (prior.failureClass === "BUSINESS") {
         // Final — retrying cannot change the answer. Same End_To_End_Txn_Id was already
@@ -212,7 +212,7 @@ export class CbeBillService {
         // echoing the original reason, which no longer describes this request.
         return mapPaymentFailure(
           dto,
-          `End_To_End_Txn_Id ${dto.End_To_End_Txn_Id} was already processed and failed: ${prior.responseDescription ?? "unknown reason"}.`,
+          `Already processed: ${prior.responseDescription ?? "failed"}`,
         );
       }
       // FAILED + TRANSIENT: allowed retry — fall through and re-run the settlement.
@@ -225,7 +225,7 @@ export class CbeBillService {
     if (settled) {
       return mapPaymentFailure(
         dto,
-        `Invalid transaction reference number ${dto.Cbe_Txn_Ref}.`,
+        "Duplicate transaction ref",
       );
     }
 
@@ -253,7 +253,7 @@ export class CbeBillService {
       } catch (err) {
         if ((err as { code?: string }).code === PG_UNIQUE_VIOLATION) {
           // Concurrent duplicate of the same attempt lost the insert race.
-          return mapPaymentFailure(dto, "Payment is being processed.");
+          return mapPaymentFailure(dto, "Payment in progress");
         }
         throw err;
       }
@@ -264,7 +264,7 @@ export class CbeBillService {
       intent = await this.resolveIntent(dto.Bill_Id);
 
       if (dto.Currency && dto.Currency !== intent.currency) {
-        throw new CbeBillError("Payment currency does not match.", "BUSINESS");
+        throw new CbeBillError("Currency mismatch", "BUSINESS");
       }
 
       // Re-run bill-query — fresh, never cached. Last legitimate point for a synchronous
@@ -272,7 +272,7 @@ export class CbeBillService {
       const billQuery = await this.billResolver.billQuery(intent);
       if (!billQuery.stillPayable) {
         throw new CbeBillError(
-          reasonToDescription(billQuery.reason, intent.referenceType),
+          reasonToDescription(billQuery.reason),
           "BUSINESS",
         );
       }
@@ -283,7 +283,7 @@ export class CbeBillService {
         Math.abs(amount - intent.amountMinor) >
           intent.amountMinor * AMOUNT_TOLERANCE
       ) {
-        throw new CbeBillError("Payment amount does not match.", "BUSINESS");
+        throw new CbeBillError("Amount mismatch", "BUSINESS");
       }
 
       const paidAt = new Date(dto.Timestamp);
@@ -341,10 +341,10 @@ export class CbeBillService {
   private assertIntentPayable(intent: PaymentIntent): void {
     if (intent.status === ProviderPaymentStatus.REQUIRES_ACTION) return;
     if (intent.status === ProviderPaymentStatus.PROCESSING) {
-      throw new CbeBillError("Payment is being processed.", "BUSINESS");
+      throw new CbeBillError("Payment in progress", "BUSINESS");
     }
     throw new CbeBillError(
-      reasonToDescription(localReason(intent), intent.referenceType),
+      reasonToDescription(localReason(intent)),
       "BUSINESS",
     );
   }
@@ -352,11 +352,11 @@ export class CbeBillService {
   /** Check digit first (cheap reject), then the unique bill_reference lookup. */
   private async resolveIntent(billId: string): Promise<PaymentIntent> {
     if (!this.billReferenceService.isValid(billId)) {
-      throw new CbeBillError("Bill not found.", "BUSINESS");
+      throw new CbeBillError("Bill not found", "BUSINESS");
     }
     const intent = await this.intentsRepository.findByBillReference(billId);
     if (!intent || intent.provider !== ProviderMethod.CBE_BILL) {
-      throw new CbeBillError("Bill not found.", "BUSINESS");
+      throw new CbeBillError("Bill not found", "BUSINESS");
     }
     return intent;
   }
diff --git a/apps/edr-payment-api/src/modules/cbe-bill/cbe-exception.filter.ts b/apps/edr-payment-api/src/modules/cbe-bill/cbe-exception.filter.ts
index a5a7055b5..5024c8cf3 100644
--- a/apps/edr-payment-api/src/modules/cbe-bill/cbe-exception.filter.ts
+++ b/apps/edr-payment-api/src/modules/cbe-bill/cbe-exception.filter.ts
@@ -40,7 +40,7 @@ export class CbeExceptionFilter implements ExceptionFilter {
       response.status(HttpStatus.SERVICE_UNAVAILABLE).json({
         Status: "FAILED",
         Response_Code: "9",
-        Response_Description: "Service temporarily unavailable.",
+        Response_Description: "Service unavailable",
       });
       return;
     }
@@ -66,7 +66,7 @@ export class CbeExceptionFilter implements ExceptionFilter {
     response.status(HttpStatus.OK).json({
       Status: "FAILED",
       Response_Code: "2",
-      Response_Description: "Internal server error.",
+      Response_Description: "Internal error",
     });
   }
 }
diff --git a/apps/edr-payment-api/src/modules/cbe-bill/mappers/cbe-error.mapper.ts b/apps/edr-payment-api/src/modules/cbe-bill/mappers/cbe-error.mapper.ts
index 98b5e8825..e2ec58114 100644
--- a/apps/edr-payment-api/src/modules/cbe-bill/mappers/cbe-error.mapper.ts
+++ b/apps/edr-payment-api/src/modules/cbe-bill/mappers/cbe-error.mapper.ts
@@ -26,5 +26,5 @@ export function toCbeFailure(err: unknown): {
   if (err instanceof CbeBillError) {
     return { description: err.message, failureClass: err.failureClass };
   }
-  return { description: "Internal server error.", failureClass: "TRANSIENT" };
+  return { description: "Internal error", failureClass: "TRANSIENT" };
 }
diff --git a/integration/src/cbe-bill.it.ts b/integration/src/cbe-bill.it.ts
index a75e897a4..f630e9a88 100644
--- a/integration/src/cbe-bill.it.ts
+++ b/integration/src/cbe-bill.it.ts
@@ -174,7 +174,7 @@ describe("CBE Unified Bill (payment service as biller)", () => {
     });
     expect(res.status).toBe(200);
     expect(res.body.Response_Code).toBe("2");
-    expect(res.body.Response_Description).toContain("already used by a different payment");
+    expect(res.body.Response_Description).toBe("Duplicate End_To_End_Txn_Id");
   });
 
   it("rejects a second debit on the same bill", async () => {