you buy multiple days of premium and total was like 11 days

I bought premium Friday and it was 11 days of premium and it ended today can anyone tell me what happened

So when ever i try to buy anything in the shop it keeps sending me to the error link http://tankionline.com/pages/payment/?type=error and i have used different computers, tried yesterday and today, and cleared my cache but still will not purchase anything... any other possible solutions?