Airtel — regarding broadband bill

The bill for 6 months was generated for which I have not opted. When I called the customer care, they kept me on hold for 30 minutes to connect to a supervisor. I had to cut the call and call back again. But of no use, I was again on hold for more than 30 minutes. I don't understand how they could give such an idiotic reply that the supervisor is busy and I have to wait without knowing how much time I will be kept on hold. Very worse service. They give all false promises. The speed is very slow and overall a useless network.