Quick update: In a bizarre turn of events, when the wireless dropped out yesterday so did the wired connection, and after reboots galore and factory defaults (with the assistance of more than one support person at Virgin) we got the wireless working but not the wired - I get lights on the ports (and PC shows cable connected) but no IP address via DHCP and if I give a static IP I still can't ping the router or the outside world.

They're sending me a new Super Hub. And they've even said they'll credit my account for the time I'm without a usable router.