Airtel — server unreachable from last 15 days

Address: Pune, Maharashtra, 411057

From last 15 days i am facing the network issue while calling i am getting the "server unreachable" error message. I have raised issue to the customer care 121 multiple times. But till they haven't responded to me. This is very disappointing. From last 11 years i am using this airtel number. And don't have any alternate mobile number, i am trusting airtel but they are not giving importance to their regular customer.