I am using Airtel Prepaid since more than one year.
I have never activated GPRS on my cell phone but still my balance got deducted by Rs.150.
I called customer care for the same more than 50 times(probably more than that),but there was no responce.
Then i visited their office and they said that my balance wont get deducted hereafter.

After couple of days it has again started.It is getting deducted by Rs.15 per day..Even today.