I am using this website android app for online price comparision as it has all prices of a product from different e commerce stores.recently they have started a referral program for its app promotion, which will give rs 100 paytm cash coupon for referring it to 5 friends, they mentioned that they will send the coupon after 5 days but it was ended up for staying for 15 days, atlast I got promo code for paytm cash, but when I try to redeem it in paytm it says invalid voucher.i did mail 4 times regarding this to mysmartprice but they did not respond to it.
Finally a fake promotion offer from a online cashback site to increase it app download.i never faced this type of problem.