Good app but theres a problem

It is a good app to learn foreign languages especially for international students but I couldnt restore purchases saying that check your internet connection or displaying "downloading" for an endless while. It is a big problem because even though your purchases are still unavailable, your money has already spent. This is a quite good app but it is not useful until it gets fixed.

yu08101k2b about Go Talk - Learn languages, v2.3.0