The following experience is based on years of experience with Freecharge & other Payment wallets
Most of the time you apply the promocode & it would not be applied!
The amount gets deducted from the bank but the transaction at freecharge fails? No worries on amount deducting twice or thrice it is automatically revered in 4 to 5 days. BUt they have to improve on their systems. This should not happen frequently!
Use this Wallet as last resort!