Amazon India — Not received full cashback on flight booking from Amazon

I booked flight ticket from Amazon using icici credit card on 10th oct. There was 14% cashback offer (9% max rupee 999 + 3% unlimited cashback + 2% unlimited reward point will be credited monthly). After few days I found that i did not receive cashback. After following multiple time with amazon customer service they agreed to pay but they paid only 3% amount. So again I called customer care and they agreed to pay remaining amount but I have not received yet. Everytime they says your remaining amount will be credited within 3 to 5 business working day but these all are false commitments. I called again amazon customer care and now they said if I provide offer snapshot then only we can proceed further. I have seen such company first time ever which ask offer snapshot from customer. Now I started tweets but Amazon social media also keep asking offer snapshot. I provided all the detail including offer snapshot but now they said we provided all cashback and they stopped responding my email and tweet.
This is very simple issue. I provided all the proofs then also they did not provide cashback.
We know Amazon is number one company for online shopping but it has very poor customer service and uneducated employees.