How can I dispute a Apple Pay payment that I have no clue about

Apple Pay is a method by which payments may be made. Those payments are associated with a credit card or debit card that you set up in the Wallet app. The bank associated with that credit or debit card handles a disputed transaction.

Are you saying there’s a fraudulent charge on one of your accounts? If so, report it to the fraud department of the bank that issued that card that has fraudulent charges on it.