Restarting Graduate, Samsung Mobile Phones Complaint

I bought a new samsung mobile phone on11.01.2012 after it has restart many times.I am taken to sakthivel electronics,samsung service center but they just software updating and change of mother board.Moreover,my phone restarted again and again so what i will do for this problem.please understand my problem for my phone problem rectification.I am awaiting for your immediate reply and action.