Mi - Not replacing the mobile

I have purchased MI Redmi note * on **/**/**
from Balaji telecom Ramgarh, Jharkhand on **/**/**. I visited the city centre Boaro- QDIGI Bokaro, Jharkhand. In my mobile, there is a problem with heating while standby.
*st WXIN************* service centre tells me that comes after when mobile temperature ** or ** above on **/**/**. I visited service centre for DOV letter but service centre loudly yelling and refusing to give DOV letter for replacement with **-degree snapshot
*nd WXIN*************.
I am very worried about the issue. Kindly do the needful because many devices are blasting due to heat. I want my replacement with Dov letter. I am not satisfied with Xiaomi service. I want my device to be replaced.