Once I had an incidence with Amazon where there was a 100/- cashback on an item and it was clearly written that I can use any payment method. So, I paid with ICICI Amazonpay card. I got the 5% cb eventually, but didn't get the 100/- cb. I complained repeatedly, but they gave the same reason that that offer was only valid on Amaon pay upi, while there was NO mention about that. I also shared the reward screenshot with them but they kept saying that for all cashback offers it is always better to use the amazonpay UPI only.... That was the only one bitter experience I had with Amazon in last 10 years. So, nowadays I remain extra sceptical with such offers.