Xiaomi India — product faulty and not solved while under warranty due to whimsical reasons

Address:

400077

My mobile handset (Redmi 5) purchased less than 12 months, and still under warranty is refused to be serviced citing 'liquid damage'. Touch screen buttons are not working, and while service team delayed firstly due to lack of availability of spare part, later asked for 'repair cost' of nearly 70% of phone value. Upon explanation that phone has never been mishandled, they said yes, but it is only due to 'excessive sweat' and this is not covered under this.
This is just an excuse to avoid repairs. I understood while in gallery that a huge number of such handsets have the same issue and its a manufacturer fault. But, mi is finding means to avoid repairs citing several such wrong reasons.
Model name - mai132