Myntra.com — cancelled order delivered on cod and myntra refusing to take it back

I had ordered for 2 tshirts on myntra on cod basis. I subsequently cancelled one of the tshirts before delivery. A myntra delivery boy came for a delivery and refused to let me open the packet and see which tshirts were there in it. So i had to pay the full amount and accept the packet.in the packet was the tshirt which i had cancelled. I placed a request on myntra on 1 august to return the product and refund my amount. They told me that the issue would be resolved in 3 days. I did not hear anything from them till 3 august and then again called them. I was again told that the issue would be resolved in 3 days. I did not receive any communication from them again. So again, i called them on 9 aug and was again told to wait till 13 august and i would get a mail from them regarding the resolution.

It is quite evident that they do not want to resolve my issue