Apple India — 5S i phone is restart

Address: Dehradun, Uttarakhand, 248001

My phone was restart again and again. I already check my phone to service center Radius in Dehradun, Uttrakhand 248001. But I am not satisfy with there feedback.Apple service center took my phon for dignose for one day. but i am facing same problem from next day. and now they are saying that Its a common problem. My i phone 5S is in warranty rite now.
I purchase it 20th Aug 2016. and now they don't show their interest to exchange my phone. my phone don't even have a single dent nor damage from any where.