Myntra.com — product exchange after availing reward points

I had placed an order for 2 sweatshirts for gifting it to someone. The order was delivered on time. There are Myntra Insider points attached with all the purchases, which i claimed for the above mentioned products too. Now i need to exchange the size to XL as it didnt fit my friend. Just because of claiming those 100 odd points, Myntra is refusing to exchange the product. The Customer care is also of no help and the escalation supervisor named Sachin is sure that he is the senior most authority to whom i can raise the concern.

I just need to get my products exchanged as these sizzes are of no use to me. Appreciate quick help on this please.