I've followed the instructions on http://helpx.adobe.com/x-productkb/policy-pricing/membership-subscription-troubleshooting- creative-cloud.html#creditcard but it gives me the error:
We are currently unable to perform the selected action. Please accept our apologies for this inconvenience. We have been notified and are already working to correct this issue as quickly as possible. Please click your browser's back button and try this action at a later time, or take a different action.
Error Number: PMT_000008
I understand your concern, in this case it will be best to contact Adobe to change the credit card information.
Please use this link http://www.adobe.com/support/download-install/supportinfo/