Don't worry they will be fixing this. The fact that thousands of players here in Japan cannot play due to billing issues is big news here. This 401 601 issue is a worldwide problem. For example, two of my coworkers have the same bank with the same basic "settings" you could say when handling payments. However, one of them can use his to play and the other cannot due to 401 601. The bank has no idea whats up and neither does SE support. Ive heard from people in a few other countries with the same or similar situations. As for me I've had it happen and managed to work around it in different ways but i can assure you it was not painless. The 1.0 system used click and buy which was not great and it too had many people with issues, but not quite to this scale. For those experiencing it theres a couple threads (more than this) going on about it. I suggest you help the others bump them up to get the issue sorted.

http://forum.square-enix.com/ffxiv/threads/86674-For-those-experiencing-errors-601-401-etc-on-Mog-Station?p=1228553#post1228553

http://forum.square-enix.com/ffxiv/threads/92573-Mog-Station-error-601-401