Reading your original post was like a complete reciting of my experience.
VM has been pretty much flawless prior to August. On Scientific Atlanta Docsis2, I was getting 20mb down, with a consistent connection.
Suddenly the whole connection dies, phone support don't have a clue, keep telling me to reboot the computer, after 2 engineer callouts both cancelled with automated cancellation messages as "faults have been found in the area", yet both of these faults were apparently fixed, and still no internet.
After a long couple of weeks, an engineer finally turns up (a day later than booked, with no explanation or apology) he storms into the house, rips out the Scientific Atlanta and chucks in a 'Super'hub, I've experience with these things before so was pleading to let me buy a motorola surfboard, or just keep my scientific atlanta, but no go.
He tells me it's cause they upgraded to DOCSIS3 (yet not one of the support techs knew of this) and the only device Virgin will authorise is a 'super'hub.
He installs the hub, runs off as fast as he possibly could (Scientific Atlanta under-arm), and now I get the crappiest connection I've had in 10 years.
This picture kind of summarises how bad this is now:
(That's wired by the way.)
I guess all I can do is switch to BT Infinity?