Sony Ericsson — Service Center not doing their job properly

To,
Sony Ericsson Team,
Dear Sir,
I have purchased a walkman series phone W710i, its IMEI No.[protected], from a authorised dealer (Digital Mobile Collection, Allahabad, Registration ID is UPTT-AD0398967 dt-1-04-06 & invoice no. 1601) purchased on 18-09-07, the handset is creating a problem i.e. it gets automatically turn off after a while, and i went to the service centre, in existing Civil Lines, Allahabad-Uttar Pradesh, INDIA.
They have kept my handset for 3 days from 27-08-07 to 29-08-07 and i m still finding the same problem again. The warranty of my handset is expiring in near future. And it seems to be that they just want to waste the time, so that they get some charge on my set as the warranty will get expired.
So i request you to please take some action so that the comsumer shold not face such problem.
Thanking You,
Yours Faithfully
Arpit Mehrotra
Allahabad, U.P.-INDIA