I am also facing this problem now. Sold my iPad 4 to someone else on December but then he sold to some other stranger later on and he lost all the stranger's contact, which left me no clue on how to contact that guy now.
Change my Apple ID password and the solution is not working.
Seek support from Apple, not working as well.
Sent email to Supercell and they are not replying yet.
I am very sure I did factory reset on the entire iPad before I sold it off. This is a really sad case for I know this is not the first time the players faced this problem, and yet no solution can be used. Sigh..
