Amazon India — not giving cashback for laptop purchase - august 14-21 week

Great chance to sue amazon india.
Purchased a latop, on august 19th, 2018.
That time there was an offer of 5% cashabck for prepaid orders.
But never got that cashback.
1) cust. Care guys saying - offer didn't get credit coz she cancelled and placed again. And offer applicable only once.
2) but no where mentioned in terms and conditions like that. Also 1 person from leadership team too confirmed me that they were wrong. And offer is applicable, any number of purchases. But he want to ask promotions team, why order didn't get cashback. Later he said, promtotions team said - the product is itself not in eligible list of 5% cb eligible asn products list.
3) then i got shocked. Then why amazon displayed that offer in that products' page, in both desktop and app.

Even after saying - many reviewers too commented - that - they didn't get cahsback and they also written why amazon mentioned that offer for that product.

- so clearly it is amazon's fault. Many such customers are now in depression state. But apart from asking them in chats/mail/phone/fb/twitter/jeff's mail, no where i can take to against this jaint company.
Any one please help in getting cashback...