If there's any specific channels that are affected, it may help prove the fault, but based on what you've said...
You have a fault somewhere that's causing poor TV signal, resulting in the broken pictures you describe. If you've eliminated a connections issue, then the next step is for you to report the problem to VM so they can either replace your box or arrange an engineer to investigate further.
The quickest way is to call VM: 150 from a landline, or 0345 4541111 otherwise.. and follow the options for "I have a fault with my TV service". The automated system may attempt some fixes and force you to redial 10minutes later, but no amount of reboots are going to solve this 😉
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