Amazon India — refund not reflected in my account

I have canceled the order from amazon and they said they have refunded my money back but it didn't reflect on my account. They said it must due poor bank updates and this is some main issue for me. This purchase was done in 21st may 2018 and canceled on that day they have refund on the next day itself but not credited in my bank account. Please contact me for account number and reference number.