Airtel — refund not received. it has been more than 1 month.

Registered Mobile--[protected]
Customer ID - [protected]
Transaction Reference Number[protected]

I made a recharge of Rs. 3000 in Airtel dth.
The amount was credited and it was showing in my account also.
But after around 3-4 weeks, I received a message that I have insufficient balance in my account. When I contacted Airtel CC, they told me that the last recharge was reversed (No reason stated). And that it will be back in the bank from where I recharged. When I asked them transaction ID from which they did the refund, the gave me the same transaction ID from which recharge was done. They have no proof of refund.
I did not received any refund.
I have contacted the CC more than 10 times, and every time first I explain the matter to CC for 10-15 minutes. Then the call is transferred to senior, where again I explain them the whole matter. They keep saying that matter will be resolve in around 24-48 hours and I will receive a call back. But neither the problem was solved, nor did I received any call from them. They even asked me to write an email to [protected]@in.airtel.com
I did the same and an automated reply came that I will be addressed soon ( email reference -- [protected])
But neither did I received any mail, nor did I got any call.

I am fed up calling Airtel CC.
If this amount was small, I might have left it, but 3000 is not a small amount.

I need this issue to be solved immediately. If they are hell bent on saying that refund has been done, they should give proof of refund (like any transaction ID), so that I can go to bank and show then the proof and ask for refund. Because the bank is saying that no refund has been done from Airtel.