Flipkart — Regarding not giving refund for missing product

I bought a Boat Bassheads 242 wired headset ORDER ID: OD[protected] from Flipkart. When I receive the package, I found nothing inside except some papers. Although the package was sealed indicating no fault of delivery person. I requested Flipkart for refund of ₹532 for missing product, but they cancel my return request twice. I am in trouble, because my my ₹532 is wasted. I am a plus member of Flipkart. Please help me in getting my refund as the return policy is going to end by 1st June 2022.