I had airtel post paid connection too from 2000 till 2005, most of the time I used to just see the bill and pay it, later in 2002 the company iam working has provided cell for official use, and I used both the cells, one keeping it personal the other as official use, even then my bills came to the extent of same as the previous approx 1000 plus, I paid few times, later I verified at the local office, its found that all the previous bills are over paid,
Later the amount was adjusted in the subsequent bill but, it becomes tough each and every time to verify the exact bill amount I through the sim on the dealer face and dis connect it with a letter to the, instead they made it as defaulter and made a cry othe what they wanted, thats air tel,
So, be aware the bill is right when you received from postpaid connections of air tel,