Celtic Heroes

I hope someone can help me out, I already send several support emails and read the forums but none of the given solutions work.

The problem is if I try to buy plat on my own WIFI, it will do the payment but I will never get the plat. After I get disconnecten from the server, and connot log in anymore while logged in on my apple account. (I can play as long as I stay logged out of the apple account)

I already tried:
- restart ipad (also the hard restart)
- delete the game, restart ipad and reinstall the game
- log in and out to my iTunes account
- done in app purchase in a diffrent app, that worked fine btw. But in celtic heroes it still didn't work
- contacted iTunes support, they say the problem is in the app

However if I log on at a diffrent WIFI-connection I will get my plat.

But how can I get it worked out on my own WIFI? Could there be something wrong with my WIFI setup? Other in-app purchasea work tho, I only have the problem with Celtic Heroes.