Rather than add to someone elses thread, it's far better to start your own...
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 you should 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.
You've not said if C5 is the SD version or HD, although it won't alter the advice given.
First check the automated faults line for any existing issues in your area that could be the cause: 0800 5610061. If nothing's reported, assume VM don't know about your fault and you'll need to call 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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