[Resolved]  Big Bazaar / Sony Ericsson — faulty mobile phone

I am vaibhav s. choramale,purchased sony ericsson w200i
IMEI no.[protected] on 25/01/2008 from big bazaar(lower parel).after 7 days of purchased there found some problem with
joystic,so i went to big bazaar they send me to service centre.
service center say that this mobile is tampered so they will treat
mobile out of warranty.but mobile open first time by service center only then how it can be tampered.i again went to big bazaar they said they will talk to sonyericsson people you go to same service center so i went there again,give mobile to them on 27/02/2008.but today also they are saying that they have not received approval from sony ericsson.today(7/3/2008) i talk to big bazaar also they are now saying that they have nothing to do with me you get your work done from sony ericsson. & sony people are not doing anything. WHO IS RESPONSIBLE FOR ALL THIS & HOW I WILL GET MY WORK DONE.