Mine worked fine few days ago and this is how I did it:
1. Buy crystals, amount depending how many months you want.
2. move to the subsricption page and use crystals to buy sub.
Did the trick for me, if still wont work its probably something at their end.
ive just bought some crystals but it still wont let me access the page, it was like this last night also. im trying to access it from the link where you try to enter the server in game. is there another way i can access it where it will work?