Sony Ericsson — Auto shutdown of mobile

Address:

Karnataka

I had purchased Sony Ericsson Xperia Neo V from Sangeetha mobiles Mantri Square on 23/10/2011.On 24/10/2011 the mobile was not working,I got my mobile serviced from Sony ericsson service center bangalore.But still the mobile is not perfect,same problem exists.Today 31/10/2011 i got the phone to sony ericsson service center in bangalore, but they didnt able to clear the problem,they only update the phone software,which is not the problem.If I ask for replacemant of the mobile,they are not responding.What should I do.Please help me in this regard.
My contact No. is [protected]
Service type:Warranty