Due to the nature of Virgin's networks faults can vary right down to individual streets. So although there are clearly problems in Dover, it may not be the cause of the issue you're having. The forum team here are always honest about utilization issues and will provide a reference number if your connection is affected.
My PC is about a meter away from the hub, hard wired and used to get between 189 and 217mb. It has been dropping since the new year and now averages between 20 and 90. This last week the highest I have got is 47mb. A lot of people I know are on Virginmedia and it seems they are all suffering speed problems. I phoned 150 and spoke to a nice chap who said that there is no point sending an engineer as the problem is Dover wide due to the old system we are on. He did say that a new system is on the cards, I think that we should have been informed, and a discount credited to our accounts. I know it is up to 200mb but i'm getting about 10%.
Yesterday afternoon services were offline for an hour or so and when it came back up I was finally on 24 downstream/4 upstream channels! The upstream is still QAM16 so there's obviously still some work to be done.