It seems to only be live broadcasts. Anything "on demand" from Sky Movies seems to be fine, although it still suffers from not looking as crisp as some other HD channels and not even close to the quality of Amazon Prime or Netflix. I guess this could just be down to the compression that Sky uses.
Thanks for your help anyway. I'll give them a couple of days on here and if I don't hear anything I'll call customer service.
HD doen't necessarily = sharp! Some films are deliberatly shot to appear softer. There was a BBC article that explained it all but I can't find it!!! Having said that, if you're getting pixellation then you've definitely got a signal problem somewhere!
Yeah, I get what you mean. Weirdly I've had no pixelation at all today and the picture seems pretty much perfect, so it's not a constant problem. Being cable TV it shouldn't be affected by weather conditions, right? Anyway, hopefully it stays good.