I have the same problem. It seems that game center has locked onto the new game my kid opened prematurely (not realizing that the backup had not taken his progress from his old device) we have deleted the game signed out of the new device, even gone so far as to turn the old device off and quit even using it! But all we get is that the barely played game asks to be the update and delete the game he spent a lot of hours and $$$$ playing. He spent all his birthday money on stuff on his old iphone 3 and now has a new 300 ipod in a drawer that he can't play because this game is so important to him.
I have read a hundred posts and the answer is always the same and no one ever addresses the question. It is as if they aren't reading what people are asking.
signing out and back in does not work.
deleting new game and deleting in gamecenter on new device then signing out on both devices and then signing back in only on old device - game asks to overwrite game with the saved game they have stored and we cant delete.
It would be easy to accidently do this (it only offers cancel or overwrite) and he would lose 200$$ worth of his game but thankfully we have not made that mistake. The game works fine on his old device but every time he opens it it offers to delete his game and replace it with the new game that has very little progress.
Also we have tried repeatedly to link the devices with the old device and then started over with the new device, logged in, downloaded game and there is the same "no progress" game with no opportunity to "cancel or overwrite" the game on the new device.
Help
I realize the post is long but I am very frusterated that this question is out there - just like this other Dad's post - but it is never answered satisfactorily and these forum type things seem to be the only place to for help. Honestly with reports on the internet about the parent company making millions per day on clash of clans and hay day you would think they would have their own support system for their cash clans and cash cows (-:
Thanks in advance for some smart persons help.