iPhone 11 Heating issue and Battery drain issue

Hello

iPhone 11 (Battery health 84%) heating issue while charging the device and using the device and sudden battery drain, without using the device battery will drain, hardly 3hours I can use the phone I am facing this issue since two weeks.

Visited services centre they restored the IOS they suggested to use the mobile battery draining issue sort out slowly. I was not satisfied with suggestions and service

Any suggestions for this issue and I want know problem of my device

Thank you

Vijay