Pixellation is nearly always the result of problems with your TV signal, and these "clusters" of channels are broadcast on the same frequency - and so would be affected by a signal fault on those frequencies.
If that is true in your case, then it confirms the likely diagnosis that you have a signal fault which only physical intervention by VM will resolve. Call TV faults on 150 or 0345 4541111 and report your fault. The agent may try to reboot your box as an extra precaution, but if you've already tried that, there's nothing different about their reboot compared with yours (well, not that would affect the picture, anyway)
Forum staff work through these threads but it may take a few days, during which time you could easily have an engineer booked or box swapout arranged, if you call.
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