Myntra.com — partial order received - now not returning/refunding money

Address:

Phase 3B1, Sector 68, KumbrA, 160067

I ordered a pack of 2 h&m jogger pants from myntra mobile app where it was mentioned about 30 day return policy. The order was not complete, one pant was missing from the pack.
I have filed a return, the myntra delivery boy refused to take it back as the order was complete.
On calling customer care, the representative said now the order cannot be returned as i have missed 48 hours window as i didnt know about this and it was not even mentioned also.

I have spend the money also, and the order is of no use for me as i had send it as a gift to someone.
When myntra cant match the standards of international brands, why it is collaborating with such big names and ruining their reputation also.