Flipkart not replacing smartphone

I've purchased a smartphone Honor 8 Pro (Cost 30000) through flipkart and after 2-3 days of usage i felt that my phone was overheating near the camera area while using the camera. So I applied for replacement for which they sent a technician to verify. The technician asked me to start a video recording before his arrival. Then after that he came and just installed a software which showed the battery temperature to be around 44 degrees which he said is not very high but even at that time the phone was very hot and even I was not able to keep it near my ear during phone calls. Then flipkart rejected my return request. Now again when I applied for the return they said that it's against the company policy I am not eligible for return but my phone is still overheating and they are asking me to visit the service centre. What's the purpose of buying online item when I have to visit the service center just after a week of purchase. It would be very kind of you if you could help me out regarding this Sir/Ma'am.