Amazon India — Delivery scam Amazon India

Placed an order for a mobile phone as a birthday gift, which was scheduled for delivery today. The phone had a flat discount on exchanging the old mobile phone. However, the delivery agent without even visiting the address cancelled the order mentioning the old phone does not meet the requirements. Now, they would neither accept the request for redelivery and paying money in advance was a mistake, but won't expect the other person to pay for the gift. Now have to struggle for a refund including the 100INR, which Amazon charges for exchange and pickup.
This also shows how vulnerable Amazon delivery service is that the delivery agent can cancel the order without the pin or otp sent to the customer.