Xiaomi India — service center denied to replace motherboard (in warranty)

I have purchased a new xiaomi redmi mi note 5 pro mobile one month ago. Suddenly the screen was damaged. I have visited above service centre for the replacement of screen. They charger rs.4600 for that. But after screen replacement, headphone is not working. I have visited again today. They said it has mother board problem, so i have to replace new mother board with my coast. My mobile is in warranty period and it has no problem before screen replacement. The service centre has damaged my mother and as mobile is in warranty period, company should replace the mother board for free of coast.

Xiaomi technology india pvt. Ltd. Priyanksha communication121, b c road, bara bazar, bivvy maerket, 1st floor, burdwan