Myntra.com — return picked up but no refund

Address:

New Delhi, Delhi, 110024

I place many orders with Myntra and mostly have no problems.
I ordered several pairs of jeans to check different colours, size and length. I raised a return request for 5 items. All 5 items were collected by agent. They never issue a receipt or get signatures for pick up so I am always worried but not had previous problem. I received refund for 4 items. When I called customer care they raised compliant, complaints response was that item not collected so no refund. I cannot prove otherwise but find it very frustrating that they cannot agree with a customer on the first time like this as I am out of pocket by 1000 rs and Myntra have more money from my orders!