Duplicate "me too" posts all moved into a new thread & combined together.
If... you've proven roaming is generally working (i.e. you have a local network connection and some network-based functions work), and you've ruled out a network-specific issue.... the next step is for a fault case to be raised by CS, into non-customer-facing tech/engineering staff.
You'll need to speak to CS, probably going through a couple of agents until you get one with access to raise INC fault cases. That INC will be the gateway for further investigations and potentially liaison with the local networks in question. It may take some persistence, so be prepared for a lengthy call and some patience. Good luck.
