The Koban card issue has been ongoing for months, and while everything with the current system with the free trial period going on right now is great, they refuse to fix the problems with their billing system.
I've tried to give them money on multiple occasions, and they refuse to accept the cards (plural) that i have. Some people's work great, but until they fix the issue, they devs are robbing themselves of income. just search for threads of a similar nature to see.