[gunner45]

The second VM engineer is wrong (and the first as well). What you have is almost certainly a problem on your access network (so local and not nationwide). What's happening is that those 13 channels are multiplexed onto a single digital transport stream, and a problem on your access network, probably a distribution cabinet, is causing degradation of the signals. You need a competent engineer to find out what is causing the problem. This is not unique, it took three attempts to resolve a signal issue I had a couple of years ago.