Xiaomi India — Not returning/ servicing my redmi 2 prime phone for last 3 months

Address:	560103
Website:	www.mi.com/in

I had submitted my redmi 2 prime (Imei no: [protected]) to infotel services, an authorized xiaomi india care centre near hazra, kolkata-26, with back camera problem on 28th may, 2016.
At that time, they had informed me that the mother board is to be changed it will take 20 days (Although, it was not written in the job sheet). However. I have not received my phone till date (Almost a couple of months). As i called them during the time, they said board is not available.
I have contacted the xiaomi india customer service several time but the problem remain same.
Service centre detail: contact no : [protected]
Kolkata mi exclusive service center, : infotel services, arya regency building, no 1, andul raj road, near hazra crossing, behind jatindas park metro station, kolkata - 700026