Money being taken and no way to stop it - lost contact details

Okay so for a while now, the money for an xbox live subscription has been coming out of my bank account. I've tried to log in to cancel it, but there's no subscriptions showing in my current xbox account. However, I have had other live accounts in the past,
and therefore I'm assuming the subscription is linked to one of those. I just don't know which one, or which e-mail address I used.

I called Microsoft support, and honestly got no help. I can prove they're taking money every month from my account, but because I don't know which e-mail address I used (and no longer have the phone number I had when I signed up) they've basically said they
can't do anything. Basically, they'll just keep taking money off me every month and there's nothing I can do to stop it, because they won't tell me which email address, or gamertag, or anything.

Please can someone tell me how I go about verifying my identity to Microsoft to try and resolve this? I have asked my bank to block the payment already but it doesn't seem to have worked and these payments are seriously bleeding me dry.

:)