Myntra and Ekart Logistics - Return request declining

I wanted to return the product because of size issues. pickup person declined the return saying that serial number is mismatching and recommended me to raise a complaint. I raised a complaint through myntra helpline, resolution provided blaming me that I am trying to return the wrong product. I am trying return the correct product.I have sent them images of shirt, price tag, bar code, images of declining. But they never cared and marked complaint as solved, I have contacted them n number of times, Everytime they say my claim has been declined,they cannot open complaint. My return request has been declined thrice. I have been going through this mental torture since ** days. I regret purchasing in Myntra.