I saw that on the other Error 401/601 thread, reposting here so more people can see.
This may only work in countries that have access to Crysta.

1. Instead of credit card, select Crysta as your payment method
2. It tells you exactly how many Crystas you need. Click on "Buy Crysta"
3. Select "Buy a specific amount of Crysta" and type the amount you need
4. Choose UltimatePay as your payment method
5. It will then ask for your credit card information, but it doesn't use SquareEnix's system, so it will work
6. Now that you have your Crysta, just use them to renew your sub and play.