Xiaomi India — handset is not working properly

Address:

400708

Due to malfunctioning of Proximity sensor not able to see or make conference call, reject call or receive a call.
Screen goes blank (Black out).
No function can make the handset OK till opposite side caller disconnect the call and there after Delay in resume.
Poor show of handset.
Customer service is not good.
Video is attached
Handset is just 15 days old and required to be replaced.