Bewakoof Brands — Lodging a complaint on refund

I ordered a product from bewakoof.com, specifically a T-shirt in size L. When I received the product, I found that the size was too big, so I immediately requested an exchange on the same day, as their exchange policy allows for returns within 15 days. They responded to my request on the same day, stating that my order would be picked up within 48 hours. However, they do not have a customer care number, so I had to rely on email communication. After waiting for the pick-up which did not happen, I emailed them multiple times (twice, thrice) to follow up. Despite my efforts, more than one and a half weeks have passed without any response from their side. I now have two T-shirts of different sizes: one which I reordered and paid for again, and the original one which they have not picked up or refunded. The amount involved is 800-900 rupees, which may not be significant, but the principle and the inconvenience are important. What am I supposed to do with the extra T-shirt? Their lack of response and unwillingness to resolve this issue is unacceptable. I urgently need a solution to this problem.