Myntra India - Not getting refund

I have ordered sherwani from Myntra. While I got delivery at my home, I was in office and I got notification regarding delivery and to avail Myntra insider points. On Myntra insider points mistakenly I doubled clicked on that to avail certain *** points of no use to me. When check product it was not fitting to me and was of large size. However, when I tried to get a refund on the same it was not showing any notification for the refund. When I contacted them they said that you have avail Myntra insider points so you cannot choose for any refund or exchange. I have explained that this was by mistake and asked them to cancel my points since it's a waste of money and resource. They are saying they can't change policies and while purchasing it was written on that refund and exchange is available.