Myntra Design Pvt Ltd - Exchange item not delivered refund not received

I had ordered two bebe belts, and received the two in the same package. I wanted to return one belt and exchange the other belt for a different size. Since, the return and exchange pick up conditions state that the item has to be returned in the ''original packaging'only, i had to send both the belts in the same package. The return pick up personnel did not check the package on receiving. Few days later when the exchange delivery guy asked for the original item, and I was unable to do so, since I had already sent the time during the return pick up. However, none of the parties are ready to acknowledge the receival of both the belts during return pick up. According to me, Myntra should have investigated the matter thoroughly before rejecting my claim for a refund or the exchange item delivery.