Indian Bank — refund from amazon processed but not credited to bank account

Address:

560051

I had ordered a kurta pyjama from amazon. I had requested for a return of the product and for a refund. Refund from amazon had been processed on 28/04/2019. They have informed me that the refund would be credited by four working days but the amount has still not been credited to my indian bank account.
The reference number provided by amazon is
911002247496320190430
Its been six days now
Kindly look into this matter.