About Apple Pay - Apple Support provides an explanation:
"How do I return an item that I bought using Apple Pay in a store?
The cashier can use the Device Account Number to find the purchase and process the return, just as they would with a plastic credit, debit, or prepaid card payment. To see the last four digits of the Device Account Number:
- iPhone or iPad: Go to Settings > Wallet & Apple Pay, and tap the card.
- Apple Watch: Open the Apple Watch app on your iPhone, go to the My Watch tab, tap Wallet & Apple Pay, then tap your card.
If the cashier needs your card details to process the return, you can follow the same steps for making a payment:
- On the device that you used to make the original payment, select the card that you want to be refunded. Remember to use the card registered within Apple Pay, not your physical card.
- On your iPhone, hold the device near the reader and authorize the return with Face ID, Touch ID, or passcode. On your Apple Watch, double-click the side button and hold the display of your Apple Watch within a few centimeters of the contactless reader.
Depending on the return and refund policies of the store, it may take up to several days for the return transaction to appear on your card statement. Apple Pay activity is also included on your card statements.
For items bought using a Suica card with Apple Pay, just return the item to the same terminal where you made the purchase. Make sure to return the item before you use Suica with Apple Pay to make another purchase."