How to report an unknown transaction from Apple?

The first thing is not to click any links in the message, then contact your bank using known numbers to verify if the transaction even occured. It is not unusual to get scam messages about transactions that were never made. The message may include links to a site that looks similar to your banking site that asks you to login in. This will only give the fraudsters your banking credentials. Another tactic they use is to provide a phone number for you to call, where they will ask for personal information such as Apple ID, Password, Banking Info.

Most importantly, do not interact with any information from the message and do not provide any personal information. Follow up using known number and known websites to contact your bank.

I would be suspicious about the message you received. Are you sure it was from your bank and not a scammer phishing for your bank or other financial information/access? Do not reply to the message you received. Contact your bank directly and ask them about your account's activities.

You need to report it to your bank; they will contact Apple. You also need to determine if your card has been compromised and get a replacement card.