[Resolved]  Flipkart — mobile exchange policy

I ordered the redmi note 7s with the exchange offer from flipkart, and chose to exchange it with my htc desire 820g+ dual sim.
I am a careful phone user, and my phone has no significant external damage.
But the person who came for delivery showed me a small (Less than 5 millimeters) scratch on the body. And refused to take the phone as exchange. It is as if he wanted a brand new phone in exchange, instead of an old one.
Why is it that such a small scratch, that too on the body, which is barely visible, disabled me from giving my phone for exchange?
Please clarify!