Guys, I think this is a bad news for us lol. This isn't an isolated case, I've googled around and found most westerner or non-Japanese have this same problem.

For those who have purchased Ark cash via credit card, can you check your statement whether Sega have billed the AC you've purchased?

I was trying to charge the AC earlier and the transaction failed, saying the card can not be used, please contact your bank. Got me wondered, check my debit card's statement, there was no billing or transaction from Sega at all, I previously purchased AC twice (5k yen and 1.5k yen) but the statement shows nothing related to Sega. Some people in the forums have mentioned that, Sega will only take the money from our credit card 30 days after the transaction, but most bank (In the western, at least) will drop the pending after 15 days. So..this could be the problem for those who are using western banks (Which I am).

This isn't the end of the world though, IF we didn't get banned for trying to scam Sega. There are alternatives around, WebMoney is one, but its expensive as resllers mark the price up.
For example, SuToCorp marked the price up to 11-13USD :/

Anyway, I'm going to call up my bank (I'm using a UK bank now) tomorrow morning and see what they say.
Ban hammer might coming my way. lol

UPDATE:
So my friend that had used Maybank debit card to purchased his AC last month, failed to purchase the AC just now.
As for myself, I've tried using both of my Public Bank credit card and Maybank card, failed too.

I think it is very likely that Sega JPN has banned the usage of oversea credit cards.