Airtel sales guys especially recharge are youngsters not knowing their work. They simply charge you without knowing that they could have done it better.
I went in for Airtel since I had an official one. Even the official one we had we always use to have problem on the billing which they made it quite complicated.
There were 3 occasions I felt cheated. One while having a free SIM card that is what they said they asked me to pay for it again.
Once I went to recharge and having done that they asked me more money for charging under seconds scheme.
One more time the SIM card went corrupt and I lost all my stored numbers as well