Amazon India — regarding cash back

Website:

www.amazon.in

Ordered motorola e4 using cod option. On getting the product the delivery guy said that if you pay using visa card you will get 10% cashback so was written on the box. Hence i paid through card. But after 1-2 week no cashback was credited and when i reached out amazon customer care they said the offer was expired on 31st oct. But i ordered the product on 4th nov and it was also shipped on that particular day so if the offer was expired than why was the offer mentioned on box and even if it was mentioned than why was expiry date for the same offer not mentioned on the box.. Don't try to fool the customer with false offer. Look in to these and solve this issue.. Also being a prime member hardly got any of the product delivered in 1-2 days.