I did recharge my number with freecharge and I thought I will get some offer but I was wrong its just a trap for people.
I have installed the freecharge app and I recharge my airtel number with 300 amount but there is no offer and nothing else for me. so freecharge service and advertisement is just for make fool to peoples.
after that I did uninstall freecharge app from my mobile and I did not try again.