Apple India — iphone 6 battery draining and heating.in warrenty but apple refuse to fix the issue

Address: Ernakulam, Kerala, 683520

Hello,
I had a n apple iphone 6 and which is only 8 months old. After some days the phone starts to heats up and getting over heated always. The battery is draining too fast. Getting only 4 hrs backup. When i charged it night 100% the next day morning the phone will be in switched off with 0 battery. Taken the phone to support icare thrice. They are telling it is expected behaviour. And i given the phone to inspect but they only re install the os and the issue still exists. I need to be fixed the battery soon. Its very disgusting about this. Kindly help apple i[censored] can. I suggest my all friends to dont use apple devices. U will regret.