I use the UPI-based cashback offers. Buy 3500 Rs GV using UPI and get 150 Rs as amazon pay balance. Or get 100 Rs for 3000 Rs GV. There are some other as well like 50 on 1000, 25 on 500 etc. The effective reward rate is 3.3 - 5%.
Since I don't have a rupay card, I can't verify if we can pay for above UPI transactions using that CC.