Can't add a new Payment method

As the title suggests I’m having issues renewing my WoW subscription.
Whenever I add my new debit card I keep encountering a “internal error” and being told to try again later. I’ve also tried doing this on the website and only being told a error has occurred.

Has anyone else had this issue? No error code is being shown.

Same issue. I have a new debit card, but on the “Add New Payment Method” screen I just have an endlessly looping loading icon. @Blizzard, help us out here.