Amazon — charge dispute

My name is yash jain and i have oredered a product of 1249rs. (Milton thermosteel bottle 1.8l) from amazon.in on 6th april 2019 and then return it on 11april 2019 due to personal problems. And on 11 april 2019 amazon initiated a refund on my card but i still didn't get the money. Amazon sent me this rreference number[protected] and told me to fill charge dispute form but kotak mahindra bank do not have such policy according to them.

So please kindly respond to my complaint as soon as possible. It's urgent.
Thank you sir