Airtel — airtel not provide services but getting billed every month

Address:

Thane, Maharashtra, 400604

I have port my number from Vodafone to airtel. But in airtel network not able to connect other networks even airtel itself. Every time given message server lines are busy.
I am not getting service then why should I pay bills to airtel.
Many times I have complain but no solution.airtel team not able to response also. Very bad service provide by airtel, this is not happening with my number even I have seen many person in my with same problem