Pixellated pictures on live TV are often the sign of a signal fault. If you've rebooted your box once, then there's likely a fault somewhere, so call VM and report it. You're likely to need either an engineer visit or a replacement box, depending on what VM's remote diagnostics turn up. They can do these while you're on the phone to them.
150 from a VM phone, 0345 4541111 from any other phone - choose the options for "I have a fault with my TV service"
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Sorry to hear of the issues that you've been having with your tv service.
I have been able to locate your account and can see that there is a problem with the signal levels as @japitts suggested above.
This would need a technician visit to resolve the issue, I have arranged for the appointment and you can find all the information that you need about your appointment on your online account and clicking My Account and Order tracking.