I had the same problem.
Started as a "free player" but decided I wanted to become a preferred player, so I bought some CC. This was no problem (I used Ideal) but after a day or 2 I decided to sub. This didn't work, everytime I tried I got the "try again later" error.
Well, I tried for 3 weeks and this friday it finaly worked.
I e-mailed them, and I got the same mail as everybody, saying I should call them. This I refused, because of the horrorstories I read on this forum about their CS. Couldn't complain here either, because as a preferred player you can't post on this forum