Picture and sound break up on ITV3.

You'll need to tell us what TV, set top box you have for us to help. In the meantime, check your aerial connections to make sure they are secure and try a retune after that. Often, doing a retune without the aerial connected, then a full retune with it connected does the trick; this 'flushes' old channel settings in some equipment. In my area, ITV3 is a bit iffy and I cured my problem by checking all my coax connections up to and including booster and aerial.