The issue is:
I had an US account which some iTunes gift card credit on it. Using this credit, I bought the game Magic 2014. I played a lot and after some time I decided to buy its expansion through an in game buy.
In the mean time between my first purchase of the game and the purchase of the expansion I decided to switch my iPad to my Brazilian account, since I got bored of buying iTunes gift cards. Since then my iPad was always using my BR account, but all my apps kept installed, some bought at the US store and some at the BR store.
In game, I pressed the buy button and bought it using my BR credit card, which was rejected. Now I want to pay for my expansion and to keep playing my game.
I need to contact apple and ask them to try to charge my credit-card again, but how do I do that? I haven't even received any email about this... it only tells me that my purchase was not processed...
What can I do?