XBox keeps submitting unauthorized charges on my credit card. How can I get this to stop?...

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.

Contact support, if you cannot remember your old Microsoft account credentials, then another way to trace that account is through verification of your credit card detail since your credit card is attached to it. Tell the agent you want to raise an "unauthorized
charge" complaint to get the charges stopped as well, should the account be traced as not of your own belonging.

You are welcome. Well, if you got a new credit card (new number, new cvv, new everything) then this might be an unauthorized charge from someone that stoled your credit card information.

Either way, if you cannot access the account, you would need to contact your bank or credit card company to request them to stop all futures charges from Microsoft/Xbox.

I keep get charged to my credit card for an account that we can not access.

You can contact your credit card company and explain the situation to them and they will initiate a credit card number change to prevent unauthorized charges to your account. Alternatively if you have set up that you need to authorize a purchase that incurs
a charge before they are completed then you shouldn't need to worry. Just monitor your credit card and if an unauthorized charge occurs then you can contact your credit card company to have it reversed. Most credit card companies allow you dispute a charge
that was not made by you within a certain timeframe. So as long as you monitor it you won't be held responsible if a charge does indeed occur.