Your purchase could not be completed

I have a problem about in game purchasing. This never happen before since a week ago i tried to make an in game purchase and the message pop up “your purchase could not be complete please contact itune support”. Then i try to fix the problem by searching on the internet but there are 2ways to fix which are contact itune support and wait until i can purchase again, the problem will be fix automatically. So i wait For a day and try to purchase again and it could be complete. However, the Same problem shows up again and its been 4days already that i cannot make in game puechase. Can anyone help me fix the problem. Thank you everyone for he help.