Online Store - Error 004 on Checkout...

I just went to try to buy a new character slot, and when I went to the checkout screen, I got an "Error 004" message, saying I should try again in a few minutes. Its been this way for the last 30 minutes (as far as I can tell, from when I first tried to buy).

The pop-up for choosing between Visa/Mastercard seems to be busted, and I'm guessing that's related to the issue. A few friends also tried the checkout but got the same error.

Keep trying or retype credit card number , happened to me ..

You should not keep retrying in cases like these. It is possible that the card transaction are taking place, you could be charged multiple times. You should have created a support ticket.