Xiaomi India — phone under warranty not getting repaired

Hi,

I own a redmi note4 mobile. It has been 6months since the purchase date, now touch screen has stopped responding. I took it to the nearest service center, they reported that there is some fungus inside the phone on the mother board which needs to be replaced and that fungus is due to some water going inside & declared my phone is out of warranty now. Now i had raised concern with the grievance team but no one is ready to respond on that mail.