cannot pay for extras in a game

Hello there! I'm playing a Cindy crash game on iPhone. Whenever I'm trying to buy extra moves or a new episode it says that the purchase is failed and no money was removed from my account. I do not know why. I have recently changed my pay details and since then I'm having problems with these purchases. Before that, I was always asked to enter Apple ID password to buy but now it goes straight to buying and always ends up with failure. I tried buying other things and all was fine so I'm sure that the problem is not with pay details. Thank you for your help!