Myntra.com — exchange order not delivered

I placed an order for my shoes on 23 june 2018. It was a bigger size, so I placed an exchange order for a smaller size . First of all it was dated to be delivered on 10 july which is too late . on 10 july the delivery boy called me when I was in office and asked me to take it. I said I will be there in 20 mins or you can deliver it tommorow. He just said "no" and cut the call. I called him again but he didn't pick up. Then after some time when I opened my myntra account it showed that "costumer refused". It is very frustrating.