Airtel — postpaid sim not working

Address: New Delhi, Delhi, 110092

I had requested to convert my prepaid sim to postpaid 499 plan. The executive came and gave a new sim with number[protected]u. Yesterday i got a message from airtel that address verification has been completed and conversion will start shortly. Meanwhile my old sim which was prepaid was stopped and there was showing no network so i changed my old sim to the new sim. The new sim is also not showing any network.
Now neither of the sim are working. This is sheer irresponsibility of airtel, they should be activating the new sim before deactivating the old one. I'm extremely upset with the service as i'm not able to make or receive any calls.