Hi nereida, I'm a Singaporean who also tried returning to the game recently and like you was faced with credit card registration problems. I used to play on an EU account without any issue, but this time round the same card which I used then is no longer valid.
I contacted POSB and what I understand from the customer service rep is that MAS has new regulations in place with regards to payment for online game content, thus payment to certain game companies are no longer approved. I think it also has to do with the added credit card security features recently implemented, and this regulation affects all local bank accounts. What I suggest is that you can try contacting Standard Chartered to ask them about the transaction you're trying to make. They should have a record of the failed attempts and will be able to tell you what went wrong.
In other news, FFXI recently announced they're switching POL accounts to the Square Enix accounts to facilitate registration
, and soon we can pay via Paypal services much like FFXIV. This will be in place sometime in July/August, so hopefully we will be able to play then. Edited, Jun 26th 2011 5:12pm by Raithlion