As others have already pointed out, pixellation is often the result of problems with your digital signal which will need either an engineer visit or a box replacement. Identifying specific channels (including HD/SD) that are affected can sometimes help narrow down the cause, but probably won't change the end result.
I can only suggest you patiently wait on the faults line, the only other viable option is to wait for Virgin staff to pick up this post which can take a few more days.
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