Samsung Mobile L700 — hanset problem

Sir with due respect,

i purchased a above said mobile on 30-09-09. Next day i went to my sister's home in the same city,
and i found there was no network. i was there for around for two hours. i also thought of their might be network problem.Again next day i was on the same place & faced same problem. then suddenly i thought to put my sim card into some other mobile set, then i was so surprised to see there was no netwok problem & i was able to call any number. from this expirence i became 100% sure that is a problem with samsung handset. I complaint to customer care & to the vendor from where i purchased it. Vendor is not ready to accept it that there is problem with handset. & customer care has directed me to do some setting changes & go to the same place & try once again.My question is that why a consumer sould do a lot of excersise spending lot of time & money. whereas i am 100% sure i purchased a sealed pack & make no changes in setting.