After porting my number from idea to airtel idea claiming 1500 unbilled amount pending

Hi
My name is Bhavna I was using idea mobile number 9867239774 I was really fed-up of 1000 /2000 bills that too not using much with idea always claims we used internet I plan to switch from idea to airtel whatever was outstanding I paid after porting in to airtel one fine day I teciev mail from idea saying I used internet I need to pay 1500 from some court I received the call then again one day they called saying 3000 outstanding what the hell are we insane I don’t understand why this postpaid companies do fraud to customers by showing unnecessary usage of internet no other reason only internet usage m tired of that calls seriously pathetic service by idea I wish this idea company to be banned.