Myntra.com — I had placed exchange in myntra but didn't get exchanged product

I had placed exchange for srisaras tank crop top through myntra e-commerce app and the exchange product is not delivered to me however the delivery boy (may be) mistakenly took the product with him and didnt give me the exchanged one. As I was not available at the place, my friend gave away my parcel. It was due to confusion may be, as at the same time another parcel was for return.
Many a time I have placed complaint and query regarding my issue but noone in myntra helpline is listening to me.
When I told them to give me details regarding the investigation they did with the logistic team they dont give me clear answers.
Kindly look into the matter as soon as possible.