s300m trouble history-Please

[spguru]

-Bought the phone six weeks ago
-Was working fine on 900Mhz (Vodafone) for two weeks
-Intermittent problem experienced="phone hangs,searching the net then restarts several times afterward says-sim crashes-sim error"
-Obviously not HW fault I suppose as brand new
-No warranty-parallel import
-Flashed with twister,tried 1.66-1.70,nothing worked
-ELCO was kindly to gave me a full flash (1.7+eep),still the same
-Since 4 weeks ago,phone's been playing up ,I'm upset cause don't know what to do.
-Bought the phone for my partner,really pissed I cannot fix it even if I do cellphone hacking for 4 years...
-Internet searched,found several people who experienced exactly the same problem.
-Finally contacted samsung over the internet.They reckon this:
" every country has different network system and has different setting with each service provider. It may not be compatiable to the local networks. If your mobile phone is still under warranty, you can contact Samsung USA or refer to the terms & conditions in the warranty card. I do not recommend you to repair as it will breach the terms & conditions, thus the warranty will be void."

Anyone has got solution or at least answer why this damn phone doesn't work properly?

Thanks for everyone in advance who shares info or opinion about this.

BR