Cloud Search [Q] 3 operator & roaming

Hi there,
i write from Italy where the "3" company has an agreement with another operator: so if I don't have signal from 3 network I can register my phone on "TIM" network in roaming mode.

All my previous phones did this automatically, now i have to do manually: at my girlfriend's house i don't have 3 signal and i must search other operator and register on TIM manually.
When i come out i must re-search operator and register on 3 net otherwise the phone will stay in roaming (previous phones register themeselves when 3 net was detected without my intervention.

I know it's a weird issue but i don't really know how to solve --> someone has any idea?