The BQM shows that you DON'T have a problem of congestion (over-utilisation in Virgin Media speak), but it DOES show that you have a very poor quality line with either power or noise problems. I would advise you don't waste your time dealing with VM's incompetent offshore call centre whose service is truly appalling (but cheap for VM, and if customers don't like, hey, who cares?).
Hold on here for the helpful forum staff to pick this up and advise on next steps. We could do a bit more amateur diagnostics with the contents of your hub's status pages, but the BQM shows a serious problem that will need a technician visit to fix.
Unfortunately you made a mistake having the Hub 4 - because this uses higher modulation rates this is far less tolerant of line conditions and noise than the Hub 3, and requires a materially higher SNR to work. I'm not sure this is understood by everybody at VM, and clearly the company don't do any checks on the customer's connection before sending the devices out.
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