We use Stripe as our purchasing partners for all credit card transactions. It's accessible in a number of countries worldwide and growing. To check if you are in one of the countries that it supports feel free to visit their site to check their list.
My purchase attempt was declined, what gives?
We have another page with some of the common causes why a purchase attempt was declined.
Until recently we allowed players to pay for premium content using BitCoin. We've had to disable this payment method recently as it was causing longer than normal processing times during some purchase attempts and this was causing some errors.
Until we can get this looked at and worked on, the payment method will be permanently down and we don't have an ETA on when it may be back or if we'll be able to get this payment method working again properly.