Have they tried but failed? If so, there are two possibilities: first, you might be too developed (do you already have a lvl-5 city?); secondly, you can't have a mentor if you had an earlier account in the game.
yes i have a lvl 5 of city and something has been wrong,administrator said i have been multiboxet ,but im not its has been mine friend account and what i must do now
The level-5 city means that you're too developed to be able to get a mentor, I'm afraid. As for the other problem, the only thing that you can do is speak to the admins and explain your situation.