Non refund of Security Deposit

I canceled my service with prepaid Airtel Mobile in the month of March. In May I received a monthly bill from Airtel Mobile saying I owe Rs.4085! I canceled the service and returned my card to the service center. I didnt use their services in the month of April and May.

My friend by mistake dialed my old phone number and someone answered to him. It means someone is already using my old phone number, and I am getting bills for that guy.

At the service center they promised to look into this but two weeks ago I received another monthly bill from Airtel Mobile. Obviously, the issue has not been resolved.

It's surprising how many people have complaints about this company. The internet is flooded with people unsatisfied with this company's services. Even leaving this company is difficult.