Bank Of India — refund of my amount in my bank account

Address:

700055

I have placed an order with a commercial site which amounted me to 747.
On 18th aug, 2018 i have cancelled the order and they processed the amount to my bank account on the very same day.
By Today, 22nd aug, i was supposed to get back my refund amount of 747 in my bank account, but haven't got it yet.
Gave the bank ref no to the bank to check the status of my refund, but they not ready to help.
Please help me get ny refund back
Savings account no- [protected]
Name of account holder: Debopriyo Saha
Bank ref no / ARN number[protected]