I always used to recharge my airtel number with freecharge and it had many offers, cashback for recharges.
But these days many offers are there but none of them are applicable for airtel recharges.
Below is one of the offer which I received from freecharge but see the last line of message.
Freecharge is offering Flat 5% Cashback on minimum transaction of Rs 50. This Coupon is valid one time per User/Credit Card/Debit Card/Net banking. Get Maximum Cashback of Rs 50 by Using the F5 code.
Not Valid for airtel Users