My channel has awful pixel break up in it. I called out the cable co. he put on some kind of gizmo and said it's fixed, nope, it's not either, still has pixel break up, and picture freeze frames.
I called out my warranty service people on my fancy 55 in 4K UHD samsung TV and had them to run it thru the paces, only QVC had the problem.
I sent a email offline to Customer Service told them to tell their TV people about it, yep, they said they would. Still have the problem.
Like bad posters and taxes you just have to put up with it I'm afraid.
I've done all I can humanly do.
Good Luck !