diff --git a/apps/edr-passenger-api/src/common/utils/payment-deadline.utils.ts b/apps/edr-passenger-api/src/common/utils/payment-deadline.utils.ts
new file mode 100644
index 000000000..1d4c286be
--- /dev/null
+++ b/apps/edr-passenger-api/src/common/utils/payment-deadline.utils.ts
@@ -0,0 +1,22 @@
+/**
+ * Single source of truth for how long a PENDING_PAYMENT booking has to be paid for,
+ * shared by TasksService (which auto-cancels bookings past this deadline) and
+ * SeatsService (which extends the seat hold to cover exactly this window when a
+ * booking/PNR is created — without this, the seat hold reverted to its original
+ * short seat-selection TTL and could expire mid-payment, letting a second customer
+ * grab the same seat).
+ */
+
+/** Maximum time (hours) a passenger has to pay after booking. */
+export const MAX_PAYMENT_HOURS = 2;
+/** Minutes before departure: cutoff for new bookings and payment deadline. */
+export const CUTOFF_MINUTES = 30;
+
+/**
+ * payment_deadline = MIN(booking_time + 2h, departure_time - 30min)
+ */
+export function computePaymentDeadline(createdAt: Date, departureAt: Date): Date {
+  const maxDeadline    = new Date(createdAt.getTime() + MAX_PAYMENT_HOURS * 60 * 60 * 1000);
+  const cutoffDeadline = new Date(departureAt.getTime() - CUTOFF_MINUTES * 60 * 1000);
+  return maxDeadline < cutoffDeadline ? maxDeadline : cutoffDeadline;
+}
diff --git a/apps/edr-passenger-api/src/modules/seats/seats.service.ts b/apps/edr-passenger-api/src/modules/seats/seats.service.ts
index 1d17e9826..b2bff14b6 100644
--- a/apps/edr-passenger-api/src/modules/seats/seats.service.ts
+++ b/apps/edr-passenger-api/src/modules/seats/seats.service.ts
@@ -5,6 +5,7 @@ import { Cron, CronExpression } from '@nestjs/schedule';
 import { SegmentsService } from '../segments/segments.service';
 import { SystemConfigService, CONFIG_KEYS } from '../system-config/system-config.service';
 import { AuditService } from '../../common/audit.service';
+import { computePaymentDeadline } from '../../common/utils/payment-deadline.utils';
 
 @Injectable()
 export class SeatsService {
@@ -625,7 +626,50 @@ export class SeatsService {
     return { released: true, holdId };
   }
 
-  async confirmSeats(_seatIds: string[]) {}
+  // Called right after a booking (PNR) is created, and again on successful payment.
+  // Extends the SeatHold(s) covering these seats to the booking's actual payment
+  // deadline — the same MIN(createdAt + 2h, departureAt - 30min) window TasksService
+  // uses to auto-cancel unpaid bookings — instead of leaving them on the original
+  // short seat-selection hold (5 min by default). Without this, the hold could expire
+  // while the customer was still on the payment page, and a second customer could
+  // hold/book the exact same seat out from under them.
+  async confirmSeats(seatIds: string[], now: Date = new Date()): Promise<void> {
+    if (seatIds.length === 0) return;
+
+    const holds = await this.prisma.seatHold.findMany({
+      where: { seatIds: { hasSome: seatIds } },
+      select: { id: true, scheduleId: true, expiresAt: true },
+    });
+    if (holds.length === 0) return;
+
+    const scheduleIds = Array.from(new Set(holds.map(h => h.scheduleId)));
+    const schedules = await this.prisma.trainSchedule.findMany({
+      where: { id: { in: scheduleIds } },
+      select: { id: true, departureAt: true },
+    });
+    const departureById = new Map(schedules.map(s => [s.id, s.departureAt]));
+
+    let extended = 0;
+    await Promise.all(
+      holds.map(async (hold) => {
+        const departureAt = departureById.get(hold.scheduleId);
+        if (!departureAt) return;
+        const deadline = computePaymentDeadline(now, departureAt);
+        // Only ever extend forward — never shorten a hold that's already valid longer
+        // than the payment deadline would give it (e.g. a second confirmSeats call on
+        // the same booking, or a hold that was already extended).
+        if (deadline <= hold.expiresAt) return;
+        await this.prisma.seatHold.update({ where: { id: hold.id }, data: { expiresAt: deadline } });
+        extended++;
+      }),
+    );
+
+    if (extended > 0) {
+      this.logger.log(
+        `Extended ${extended} seat hold(s) covering ${seatIds.length} seat(s) to their booking's payment deadline`,
+      );
+    }
+  }
 
   // Delete the Journey (and its JourneySegments) scoped to this booking.
   async releaseSeats(bookingId: string) {
diff --git a/apps/edr-passenger-api/src/modules/tasks/tasks.service.ts b/apps/edr-passenger-api/src/modules/tasks/tasks.service.ts
index fb9957b92..4fb3a4f0f 100644
--- a/apps/edr-passenger-api/src/modules/tasks/tasks.service.ts
+++ b/apps/edr-passenger-api/src/modules/tasks/tasks.service.ts
@@ -3,11 +3,7 @@ import { Cron } from '@nestjs/schedule';
 import { PrismaService } from '../../common/prisma.service';
 import { SmsClientService } from '../notifications/sms-client.service';
 import { CurrencyService } from '../currency/currency.service';
-
-/** Maximum time (hours) a passenger has to pay after booking. */
-const MAX_PAYMENT_HOURS = 2;
-/** Minutes before departure: cutoff for new bookings and payment deadline. */
-const CUTOFF_MINUTES = 30;
+import { MAX_PAYMENT_HOURS, CUTOFF_MINUTES, computePaymentDeadline } from '../../common/utils/payment-deadline.utils';
 
 // Retention windows
 const OTP_RETENTION_HOURS = 1;
@@ -16,15 +12,6 @@ const AUDIT_LOG_RETENTION_DAYS = 365;
 const WEBHOOK_EVENT_RETENTION_DAYS = 90;
 const GATE_LOG_RETENTION_DAYS = 180;
 
-/**
- * payment_deadline = MIN(booking_time + 2h, departure_time - 30min)
- */
-function computePaymentDeadline(createdAt: Date, departureAt: Date): Date {
-  const maxDeadline    = new Date(createdAt.getTime() + MAX_PAYMENT_HOURS * 60 * 60 * 1000);
-  const cutoffDeadline = new Date(departureAt.getTime() - CUTOFF_MINUTES * 60 * 1000);
-  return maxDeadline < cutoffDeadline ? maxDeadline : cutoffDeadline;
-}
-
 function fmtTime(d: Date): string {
   return d.toLocaleTimeString('en-GB', {
     hour: '2-digit',
@@ -192,6 +179,7 @@ export class TasksService {
           },
         },
         paymentIntent: { select: { method: true } },
+        seats: { select: { seatId: true } },
       },
     });
 
@@ -205,9 +193,21 @@ export class TasksService {
         const paymentDeadline = computePaymentDeadline(createdAt, dep);
         if (now < paymentDeadline) continue;
 
-        // 1. Release held seats (Journey rows are the occupancy source of truth)
+        // 1a. Release held seats (Journey rows are the occupancy source of truth once paid)
         await this.prisma.journey.deleteMany({ where: { bookingId: booking.id } as any });
 
+        // 1b. Also release the SeatHold(s) covering this booking's seats — SeatsService
+        // extends these to the payment deadline when the booking is created, so without
+        // this they'd otherwise keep the seat locked for up to MAX_PAYMENT_HOURS even
+        // though the booking is now cancelled. Scoped to this booking's own schedule,
+        // since the same physical Seat row is reused across other recurring dates.
+        const seatIds = booking.seats.map(s => s.seatId);
+        if (seatIds.length > 0) {
+          await this.prisma.seatHold.deleteMany({
+            where: { scheduleId: booking.scheduleId, seatIds: { hasSome: seatIds } },
+          });
+        }
+
         // 2. Audit record (no refund — payment was never completed)
         await this.prisma.bookingCancellation.create({
           data: {