I would also see this article: About Apple Pay - Apple Support
When you view your card in Wallet, you’ll see the last transaction for each credit, debit, or prepaid card, including Suica in Japan and Apple Pay Cash in the United States. To see more, tap the card and tap . Then tap the Transactions tab. Depending on your bank or card issuer, you might see only transactions made from your device. Or you might see all transactions made from your credit, debit, or prepaid card account, including all Apple Pay devices and your actual card. You can also see Suica transactions in the Apple Watch app on your iPhone.
Some banks or card issuers provide only initial authorization amounts to Wallet, which might be different from the final transaction amount. You might see different transaction amounts in Wallet and your statement from locations such as restaurants, gas service stations, hotels, and car rental companies. Always refer to the statement from your bank or issuer for final transaction details. For Apple Pay Cash, you can get a statement sent to your Apple ID email address.
Suspend the card in question and contact your card provider to deal with the charge. Sorry you had to go through this.... :/