Maybe their plan is to wait until enough people get fed up and leave their service that the problem will fix itself
In a word, yes. That BQM illustrates a classic over-subscription profile, caused by more customers/internet traffic than the local network can support. Fixing this is expensive, and VM will only do that if there's a guarantee of being able to sign up many more customers, which is not normally the case. So, having over-sold beyond the capability of their service, the solution is to deny there's a problem, and wait for sufficient customers to leave and bring traffic down within acceptable limits. Time to investigate your options for other ISPs.
If you're locked into a contract, VM will want an early termination fee if you leave. If this applies do a series of (ethernet connected) speed tests at peak times, and hope that they are below the minimum guaranteed speed, because then VM either have to fix the network, or release you from contract without penalty.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks