Myntra.com — refusing return

I had ordered a pair of dorothy perking trousers but it turned out too big for me so i decided to return it. Myntra refused pickup saying original tags are missing. All original tags that i received are intact and attached to the trousers.
I have reached out again and again to the customer support but they are unable to help. I have already shared the pictures of tags received with myntra. The trousers are unused and in the same condition as received. Myntra does not have the smaller size available so it can't even be exchanged.