Amazon India — Unethical behavior and dubious offers

Hi,

Amazon India recently was promoting samsung home appliances by giving 5% cashback on the second samsung applicance purchased 10 days after the purchase of the first samsung home appliance . accordingly, I purchased the samsung refrigerator on 5th july. I collected amazon's partner offer and then placed an order for samsung washine machine on 19th july ie after 14 days gap. They were supposed to refund 5% cashback. But till now, I haven't received any amount from them. I even tweeted in twitter. But they have chosen to ignore. Please help.