Sub: unusually high GPRS bill and no SMS alert after 1 GB usage.

I am post paid customer. I have got my Nov month bill on 24th Nov 2011. I used GPRS from 11th Nov to 18th Nov 2011.

1. In my Internet bill details, 15th Nov shows total 1210.90 rs usage. 17th Nov shows total 4726.8 rs.
In bill, timing is also very odd (early morning 2 am), I was not using Internet that time.

2. Also, When I crossed 1 GB limit, there was no message from Airtel to indicate over 1 GB usage.

When I requested Airtel to send me download detail for 15th Nov and 17th Nov.,Appellate Officer said No( interaction Id:968293313, on 28th Nov. 2011) He said Airtel does not show usage data to customer. He is the highest authority of escalation and there is no process to show my data to me. All I want to see is, 15th and 17th Nov data.
I cannot take word of customer executive or nodal officer that my bill is correct. I need proof.
How can I see what was downloaded on 15th and 17th Nov? Also Airtel shall pay for their mistake for not indicating more than 1 GB usage via SMS.