Uber India — Promo code

I had entered a promo code, when I wanted to book a ride the app was asking for update. So I updated it but later didn't got my discount coupons of Rs.50. I had to pay full amount. Where had my coupons gone?
Would I be able to use those coupons or not?
Other services are better and I don't have any complaints about it, but just look out for this coupons and discount options.