W02 is a typical "loss of signal" error code, and the advice is the same as dealing with any "My picture is pixelating" query. It's likely that other channels will have the same error but you've not spotted them yet! Try More4-HD or Sky Documentaries HD for size.
If you've rebooted your box once, then there's likely a fault somewhere, so this will need VM to intervene. You're likely to need either an engineer visit or a replacement box, depending on what VM's remote diagnostics turn up.
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 ideally 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". Alternatively you can wait on here for staff to respond, which may take a day or so.
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