FFXI players are going through the same thing, only they can't use game cards to pay for their subscription. Their only option is to pay with credit cards, which SE will not accept, so the FFXI players who get this error are just shit out of luck and can't play at all. It's really absurd that this problem has persisted for so long with no recent response or fix from SE.

Thread for reference
http://forum.square-enix.com/ffxi/th...yment-problems