Xiaomi India — Problem in repair.

Address:

Mumbai City, Maharashtra, 400706

I bought my redmi note 3 from amazon like 2-3 months ago. After a month or so my phone started to restart. After 2-3 visits to their service center they reinstalled the software, but the problem wasn't solved. They asked me to submit the phone, so i did. They gave me a period of 10 - 15 days. But now it's been 21 days to be exact i haven't heard from them. Whenever i call they disconnect the call and never give a specific answer. After numerous calls to their customer care they launched a complaint on my behalf 3-4 days ago, but i still haven't received any call or message. I have also heard mentioned above things from many other consumers. Please help me out