Consumer payments attorney here. A 43,039 dollar dispute through Apple Pay warrants professional legal assistance, so let me outline the framework you should understand before deciding next steps.
Apple Pay itself is not a payment method. It is a digital wallet that tokenizes your underlying credit or debit card. This means your dispute rights are determined by the card type, not by Apple Pay. If the underlying card is a credit card, you have robust dispute rights under the Fair Credit Billing Act, which limits your liability to 50 dollars for unauthorized transactions and gives you the right to dispute billing errors within 60 days of the statement. If it is a debit card, the Electronic Fund Transfer Act applies with more limited protections.
At 43,039 dollars, this is a substantial amount. Your first step should be filing a formal dispute with the card issuer, not with Apple. Apple will simply redirect you to your bank anyway. When filing the dispute, submit a detailed written statement explaining the nature of the dispute, attach all supporting documentation including receipts, correspondence with the merchant, and screenshots of the transaction details from your Apple Wallet.
Under Regulation Z, your card issuer must acknowledge your dispute within 30 days and resolve it within two complete billing cycles, not exceeding 90 days. During the investigation, they cannot report the disputed amount as delinquent or charge interest on it. If your issuer is not following these timelines, that itself is a violation you can report to the CFPB. For an amount this large, I strongly recommend retaining an attorney who specializes in consumer financial disputes. Most offer free consultations and many take these cases on contingency.