Myntra - Wrong product received and refusing to give refund

I ordered a flying machine jeans (size **) on myntra and what I received is a Arrow trouser (size **). I received the wrong product on **/**/** and on the same day, I put a return request on myntra. The delivery boy came the next day but rejected the pickup saying that I need to get approval from myntra and only then he can take back the item.
After that, I sent mail to Myntra attaching the pictures (with tags intact) of the wrong product but after somedays, they rejected my request. I again put up a request by calling then and then on **/**/**, they called me to tell that they cannot take back the item as correct item was delivered by them. I again requested a return on **/**/** but delivery boy refused to come for pickup saying that he cannot take the wrong product until I get approval.