Last year, I came to know about Freecharge by one of the friend.
I signed up on freecharge and used it some times. After few periods, I received an email containing 100% Cash Back coupon. then I again recharged my mobile using freecharge.
And then I only using it whenever I get a cashback coupon or offer in my email.
I am very happy with freecharge as there is no one giving such a great offers.
Thanks