Apple India — In warranty battery issue still facing issues

Address: Gurgaon haryana

I have visited twice to apple store for complaint that my phone battary is 86% im not getting back up of my phone, and my phone is in warranty 3-4 hrs is my maximum battery back up .
After full charge
They are not changing my phone battery and due to which i have to suffer a lot .

Serial no -G0NC1H8YN73D
Imei no[protected]
Mobile no - [protected]