Amazon India - Coupon not applied on checkout

I made a purchase on Amazon a Samsung Galaxy S** FE *G mobile phone via order number xxxxx on **th Apr **** for Rs.**,***/-

I made the payment using amazon pay balance. The order was delivered in good condition.
Problem / Issue raised :
Before placing the order, I was shown a coupon on the app which claimed that Rs.**** would be discounted (PFA for the view on the coupon). However while placing the order, the coupon had removed itself due to some technical snag/ glitch. As a customer, I did not realize the coupon being removed and clicked pay using amazon pay and the amount got processed.

Upon my realization that the coupon has not been applied , I immediately brought to the notice of the amazon agent through chat the very next day ( available in the amazon mobile app) and I was initially told that they can see that the coupon has not been applied and assured that I will get the benefit by **th May **** and asked to me to wait until then.

I sincerely abided and waited till **th May ****, since there was no credit of ****Rs to my account , I did a chat again on **th May and this time I was informed that I am not eligible which came as a complete shock.

If I am not eligible why will amazon take ** days to respond that too upon my request on chat they informed that am Not eligible. Why did not they say on day* of my complaint ? Atleast, I would have returned the phone and bought again with a discount !

After**th May my option to return was also closed as it should have been done before *th May .

Now, my point is why amazon doesn’t listen to customers who are genuine and have been a regular customer with amazon ? ( please check my history of purchase , I would have already done ****** worth of transaction in the last * months )

I requested on the agent on chat to arrange for a call to place my side of the complaint and why a technical snag should devoid me of my coupon discount of Rs.****/- the char agent said there is no option for them to arrange for a call back.

I raised the concern on Twitter (trail Mail has my response ) and have been following up for a call from an executive who can hear my complaint and ensure that I get my discount of Rs.****/-

I am surprised that Amazon is hell bent on closing the Twitter feed with an immediate response of check the email which I had already responded saying the email doesn’t have anything more than what I have heard and it keeps saying am not eligible without understanding the exact issue related to my case. Even after a follow up for more than * days on social media, not even a single call has reached me. I am still surprised that Amazon which has such a big reputation to itself and claims as a customer centric organization is least bothered about a customer complaint. The agents just close the customer complaint with the same response and doesn’t show an empathy towards a customer who has been involved with amazon as a buyer for a long time.

The last time I raised again on social media, the executive responded Back asking me to go and fill the form again which was sent earlier . I don’t understand why the agents are playing around ? Why can’t they take the customer details directly ? Why again and again in the same issue and Twitter post they are just closing the issue in an inappropriate manner making the customer feeling helpless?

I searched online and found your email id . I hope you will be able to understand the issue and help me get my Rs****/- coupon discount which was not applied at the time of purchase due to technical glitch.