Amazon - Eligible Cashback Amount Denied

I had booked a flight ticket on Oct **, **** on which I was eligible for a **% cashback in * parts. *% - * business days; *% - * business days and *% - on my Amazon Pay CC. The *% cashback amount is not received until date. When asked from Amazon, they are stating multiple excuses - you didn't collect a coupon, you had to pay via Amazon Pay etc. It's been more than * month with **+ calls, **+ emails for this follow up, but they are not providing my eligible amount. I have screenshots from the app, clearly stating that I had to pay via Amazon Pay CC or any other payment method to get that *% ( which is now reduced to *% as E-commerce companies keep on changing such offers).
I have all the evidence to prove that I am eligible for that amount but this ignorance and repeated false promises from Amazon is leading to mental agony and is disturbing my social as well as official life. I even wrote to Amit Aggarwal on twitter but all in vain.

Kindly assist in getting me my eligible cashback amount along with the compensation for this mental agony caused in the last one month.