unlink duplicate link from game center id

I have a game app linked to my game center id for years. I have played this game to level 823 so far.

Two weeks ago my iPhone spontaneously decided to start a new instance of this game at level 1.

So now I seem to have two instances of the same game linked to the same game center id.

This should not be possible.

My iphone is clearly confused about which game instance to load.

I explained this to the game vendor.

The game vendor says I should contact apple support to fix this.

What can be done to unlink the redundant instance of the game so that I can continue normally with my game?

Maybe the game vendor is not using the game center id correctly.

My original game was bound to a global game server. I suspect that the new instance is bound to a european server.

My me the game center sees the two instances as identical when in fact they are different versions for each server.

Otherwise, how could two instances of the same game be linked to the same GC id?

What can be done to find the root cause and prevent this happening again?

If it can only be fixed my the game vendor, can you talk to them directly?

Thanks for listening. I look forward to your solution.