Its not a bug. You have to proof that, you are the legit owner of this account and CS will help it recover from you. If you account was hacked, plz send a mail to mobilelegendsgame@moonton.com, and fill up the ticket correctly. Hope you get your accohnt back.
Additionally, we apologize but account issues like this are beyond our powers. Your only hope is to actually answer and follow what is being asked by the Customer Service. Like what seimz said.