trying to find a fraudulent charge on my card

I suggest you directly check with your bank as for transactions, on Microsoft's side, not much can be done without more details of the charge. Get more information about the charge at your bank and then contact the Microsoft support team.

A representative should be able to search with the full card number and at the very least remove your card from the account to stop any future charges to that account unless they add the card back to their account.

In this case the best thing to do is to call your bank and have them put a stop to the card itself.

Hello pantytheif,

If you already reached out to a Microsoft Representative, there is not much that I can think to do on Microsoft's side. I would recommend reaching out to your bank and cancelling your card/getting the unauthorized purchase refunded.

If there is anything I can do to further assist you, let me know!

Capital One is reporting fraud and continues to reverse all charges from MicrosoftXBox. The problem is that whenever they issue me a new card, the charges just continue onto the next one. And MicrosoftXBox seems to not be able to find ANY info when given
the various credit card numbers that were used by someone to charge fraudulently. So I have deactivated my latest card and will not replace it.

I agree. That was my issue --- fraudulent charges on the credit card. I contacted the credit card company, and they addressed the problem. Unauthorized charges and a compromised card number may be what happened in your situation, too.