My Xbox Live Gold subscription doesn't work

Are you sure it was not a Game Pass code?

If you have activated the code, you need to restart the console to save the code and activate it in your account then Xbox Live Gold will work.

It seems that you have the wrong card fornwhat you wanted try to contact Support

That is strange since prepaid cards are different for gold and game pass.

If you're sure the card was for gold, I'd say try to contact support to check the code:

https://support.xbox.com/contact-us

This link will give you step by step directions to cancel auto payment. If this method doesn't work, you will have to call Xbox support.

support.xbox.com/.../cancel-xbox-live-gold-subscription