How can I get a refund for a fraudulent Apple Cash payment?

Did you send Apple Cash to someone through Messages? Those are a private transaction between 2 parties only, which is why Apple says to only send/receive money with people you know. It is just like giving someone on the street $100, where your only recourse is to ask them to give you the money back, your bank surely will not refund you.

• Apple Cash person-to-person payments are like any other private transaction between two people, so only send and receive money with people you know.

Send and receive money with Apple Cash - Apple Support

If this was a merchant charge using the VISA payment network, then who is the merchant? Those are disputed the same way as any other VISA/Mastercard transaction. That is different than a peer to peer cash transaction, where there are no (or very little) protections.

Apple Cash doesn’t generally offer fraud protection. However, depending on the nature of the fraudulent payment you might be offered some relief. Can you explain what happened?

That you’ll have to prove. Apple Support documents say otherwise. I’m a former Apple Store manager and I’ve never seen that ever. I guess make an appointment at an Apple Retail Store and have an Apple Store Genius or manager write up a service document that your iPhone is defective. You need to demonstrate to them that Apple Cash is setup and active and then turn off the passcode and demonstrate that Apple Cash is still active. Then submit documentation on official Apple service forms. Good luck.

When a passcode is turned off all debit and credit cards are removed from Apple Wallet. The loss of your iPhone is irrelevant if there’s no passcode, because Apple Cash is inoperative. Sorry!