Amazon India — delivery boy cancelled order without proper justification

Address:

Mysore, Karnataka, 570012

I have ordered redmi note7 pro from amazon.in on the 28th aug 2019 with an exchange offer, the product was attempted to deliver on the 30th aug 2019. The amazon delivery boy have came to my place and have checked out the exchange phone and found it to be satisfactory.
Even though the delivery boy cancelled the delivery and given the reason like old phone exchage verification failed because imei number is not matching. When we asked delivery boy to show the imei number for confirmation, it was matching with my old phone which iam applied for exchange offer. But still delivery boy rejected order. Finally delivery boy told no issues with ur side, but verification failed. So can not delivery the phone. We will check with supervisor and we will deliver tomorrow. But finally he cancelled the order. We have contaced amazon customer care. They dont have proper justfication for this order cancellation.
Now i want ask amazon that, why the verification was failed even though we had given correct imei number after multiple checks. First of all imei validation will fail if we gave wrong imei while ordering for particular model.
Dear, amazon, be truthful to your customers and don't let them suffer by simply cancelling the order without proper justification.