About this time last year I posted about this same issue and a year on and it's exactly the same. A week or two ago I got a phone call trying to get me to upgrade and I told the guy all about the issues. Even the basic channels don't work. Channel 5 gets W02 and several others. Other channels are unwatchable as heavily pixelated. I was told my Tivo box was so old a that I needed to update it so agreed reluctantly to pay more per month for a newer box as it would solve all the issues. The box has been in place now for about a week or so and I have exactly the same issues. The additional channels I am getting are not worth extra money as so many of them do not work. The Internet is supposed to be superfast but that actually seems to have slowed down. I don't want to be paying more when I can't even get what are essentially freeview channels.
I'm pretty sure you've already tried this, but please can you check that your box is connected correctly.
Make sure the white cable is firmly connected to theback of your TV box and the Virgin Media wall socket.
From the wall socket follow the white cable making sure it's tightly connected to the splitter.
If the TV box is connected to the Hub, make sure the white wire going into the Hub is tightly connected and the Hub is in the upright position.
Then perform a reboot.
If you then still have the same problems you need to call 150 from your Virgin landline, or 0345 454 1111, so they can perform system tests. It's best to call around 8am as that's when it's least busy.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali