Lenovo — Lenovo k3 note home button, back button not working

Address:	Bangalore, Karnataka, 560059
Website:	support.lenovo.com

I bought a lenovo k3 note smartphone from flipkart on march 2016, due to some bad performance i requested a return. Flipkart got me a replacement after 15 days. Now again problems related to home button, back button and the recent task button started to occur. I contacted the lenovo support, they told me to get it to the nearest service center. When i googled for it, i came to know that there is only one service center which is located in indiranagar, bangalore.
I read it in customer feedbacks that the service quality of that service center is worst. Many say they went there with one problem in there device, the problems were fixed but new ones started to show up. I even tried reaching them many times but they never picked my call. Buying a smartphone itself is a ver big deal for some in that too problems starts to occur. Why should i risk my phone by going to that service center. I need a door service for my smartphone. The phone is under warranty so the service guy shouldn't charge.