Amazon India — to file charge dispute for my cancelled order

Address:

600102

I order a camera worth 20990 on amazon india using my indian bank debit card. On the same day i cancelled my order and they intiated refund same day itself on 16/01/2019. With the reference number[protected]. But its been more than 15 days the amount is not credited on my account. The amazon want to file charge dispute for further move. But indian bank, my branch and customer care is not giving proper response. I want to file charge dispute for my money refund