To issue an update on this issue.
I have now had an engineer around, on wednesday. They have established that the power levels are fine, they even boosted them slightly. So, they replaced the super hub. Didn't give me a superhub 3 though, which was disappointing.
Typically, the activation system was having issues, so the engineer couldn't stick arround to check it afterwards. About 2 hours later the activation went through. Speed was no different.
As of 7pm yesterday (Thursday) the service has completely gone. The superhub won't connect to virgin media at all (Tick on super hub continuously flashing double arrow is solid green). Superhub status page indicates the issue with with the provisioning stage.
Called up the call centre, they identified that there was an issue with my box connecting to the network, and they would look into it to see if it was a network fault and that they would all me back in 2 hours or so. They didn't, so I phoned them up again, and I am told that another engineer would be needed to see what the issue is. The earliest appointment is Wednesday. I.e. 5 days from now. This is really quite pitiful, and Virgin Media should honestly be ashamed.
Oh, how great it will be when Ofcom acts on it's proposal for automatic compensation for service outages. You'd owe me £30 for this outage, assuming it doesn't come back on before the engineer arrives.
http://www.which.co.uk/news/2017/03/automatic-broadband-compensation-proposed/
=================================================================
Kind Regards
Cori
My Internet is worse than it was in 2013.

I am pleased to announce I will be switching from VM.
I am not a VM employee. My IT knowledge is pretty good though.
If you find my answer useful, please sent Kudos. If I solve or answer your question, mark as helpful answer!