I used my CC on this account and it works just fine. I wanted to use the same card on my roommate's account but I got the 401/601 errors. So, I bought a game card for my second account and it is also being declined. Please fix this soon Square-Enix.

Square-Enix says that it is an issue with my credit card company. I called them and confirmed that it was not. I then proceeded to use the same credit card to buy a game time card from Walmart.com. I had no issues using the same credit card on Walmart.com. Now, I have a valid game time card, but that is also not being accepted by square-enix.