I can't buy apps on my iphone?

I can't buy apps from my iphone it says to contact I tunes store support to complete this transaction. Does anyone know why?

You have to make an iTunes account, then buy apps using that account.
If still it doesn't work, you can try backing up your phone, then restoring it to the same firmware.
Btw, is the problem in buying (using the phone itself) or is it in syncing apps that you have bought before to the phone?

It's happening with me to I can buy in app stuff on clad of clans but I can't buy minecraft it says to contact support