Problem using my webmoney to buy Arks Cash

[Immovable One]

I asked this question in the qiuick questions thread, but since it wasn't resolved and seems to need further help, I decided I need to post a thread about it.

So yesterday, I got myself 5000PT worth of webmoney from Sutocorp. I entered the code they gave me on Webmoney.jp and got the 5000 points in my wallet - I know I got it since it says on the top of my webmoney account page in big letters 5000 POINTS, and below it is what seems to be a 16 digit number that I believe would be used when I am going to spend these points.

Excited, I went to the PSO2 site to log in to my account and get me the 5000 yen worth of arks cash since that package contains additional arks cash compared to the 500 and 1000 yen packages. I selected the amount I want, then selected webmoney as my payment method and got brought to the webmoney login page - naturally to login to my webmoney account, use my webmoney code, and pay for my arks kash. I even see on the top of the page something like 5150 arks cash for 5000 yen.

Step one (ログイン情報の入力) is obviously the login - I enter my username, password, and security code. This takes me to step two (残高不足) which is where I get stuck - it's showing me something like this:

ウォレット残高
5,000 POINT （限定 5,000 POINT含む）
------------------------------------------

利用可能残高 0 POINT

あと　5,000 POINT 必要です。
[ ][[ ][ ][ ]

My Japanese is just slightly past beginner level, but this seems like I have 0 points in my webmoney funds and that I have to enter a 16 digit prepaid code to retrieve points which I believe I DO have, so I copied the code from my webmoney page (the one on the top of my account, below the large 5000 POINTS words), and nothing - nada. I get taken back to the same page with this message above the 16 digit entry field:

プリペイド番号を正しく入力してください。

So I contacted SuToCorp about it before I went to bed, and got a reply in the morning saying that they can't help me because they got no experience with the game (though honestly, I got a feeling they misunderstood, and I may have to contact them again later today with a better written message).

So yep, I'm stuck, and possibly have money I can't use.

EDIT: Sent another (better written) email to SuToCorp, and got a reply saying they can't help me and just ask around message boards