By using free charge you really get free recharge for next time.
I normally use to recharge outside shops, later I started using some online sites for recharge my mobile services. One of my friend recommended me to use the freecharge so that I will get cashback in terms of recharge. Then I registered with freecharge and started using it. Main thing is almost every month twice I will receive an email saying recharge for 50 and get 50 cashback so for paying 50 we will get recharge of rupees 100 which is really good.
Even freecharge wallet amount you can use for some online shopping too, so there is no rule to use the cashback amount only for recharge which is another best option by the team.
I really recommend to use if if you regularly uses sites to recharge online.