Freecharge is actually cheating with its customers.
Freecharge does not have the feature to validate debit card like paytm and mobikwik. Also they usually keep on running same promocodes for long time.
What they actually do is that when u use same card for same promocode, they process the transaction but then they send mail of sorry for NO cashback can be processed.
Problem is in their process. but finally we are suffering.