[Resolved]  Airtel - Hyderabad — Not receiving incoming STD calls

I have been using the Airtel SIM ([protected]) since 24th April 2009. I am not getting incoming STD calls (only one or two people are able to call me) from the beginning, whenever anybody is calling they are getting the message as "This no. does not exist."
I have raised online log in Airtel site on 12th June & I contacted Airtel many a times but every time they are telling that this issue is escalated to some or other dept. Till date the problem is not resolved & I am unable to receive any STD calls.
I have spoken to Airtel people in all hierarchy - right from customer care to escalation manager. Everybody is saying that this issue is escalated & none of them are giving a concrete solution. I have always been assured with false commitments like it will be resolved within 24 hours/48 hours.
Today I was told that this issue is resolved, but all in vain the issue is still the same.