Apple India — problem with iphone 7 256gb

Address: 411003

+91 [protected]
I have iphone 7, 256 gb.in the morning when i was trying to dial it was not happening. Instead phone was getting off on its own. I switched on and tried sending an important msg. But i could not do so as the phone was getting heated up and moving to starting screen. Its battery got discharged from 100% to 1% in i hours time. Please resolve as i have an important event cannot function without my phone.