samsung SGH i900 MOBILE — NOT WORKING PROPERLY

Address:

Thane, Maharashtra

purchased subject phone on 11=.05.2010 from vashi Navi Mumbai .Had problems with 3g services &Video calling from first day ,

had approached samsung customer care ( Vashi ),they serviced my hand set but after that started another big
problem - now i cannot change the sim card , if i use another sim card the handset does not accept- i have to go
to the service center where they do some software changes then i can change
the sim card .
1) this is not acceptable to go to the service center for change of sim card
2) service center is quiet far from my place -need 30 min to reach.Hence i request you to please advise / suggest
for service in order to upgrade in order to rectify the problem where i can normally change any sim card at my convinience
( which is necessary as have many sim cards for traveling abroad)
or else please replace this handset with a new one