Amazon India — No Cash Back on iphone 5s

Address:	Bangalore, Karnataka, 560103
Website:	amazon.in

I bought an iphone 5s on 24th feb under the offer - "http://www.amazon.in/b?ie=UTF8&node=[protected]" Offer details: 1.Pay with HDFC credit card with 12 months EMI option 2.from Cloudtail Seller 3.between 23rd feb to 1st march My order ...satisfies all the conditions . I was supposed get the cashback of 8400 rs by 1st june but didn't. There has been more than 15 emails exchanged and 20+ phone calls, each time i have to explain them the issue from scratch and in return i get one of the following replies: 1.will be given "in 2-3 working days" 2. it is already given 3.And the last time I called they crossed all the limits saying "my order is not eligible at all" can anyone help?