Amazon India — Cheated in cash back offer on amex card during 8th-9th nov 2015

Address:	Bangalore, Karnataka, 560067
Website:	www.amazon.in

Consumer details: full name- vinay shankar prasad, registered mobile number: [protected].
During 8th to 9th november there was 15% cashback offer (Purchasing through mobile app) on amex card (Offer link-http://www.amazon.in/b?Ie=utf8&node=[protected]).

I purchased two items in a single transaction (Amount: rs. 9598/-). As per the offer i could have got it rs. 1439.70, on 9th of feb.
But till now they have not given any cash back in any form, i am calling from past 3 weeks, all customer care executive have different approach to handle it. But no one is ensuring about the cashback money. Some one is telling i was only eligible for rs. 200, some one is telling i was not eligible for any cashback as i have done the payment in two transactions mode.

I have attached my amex card transactions details.