Main box squealing through main tv

My main box, every couple hours squeals, and puts a high pitched screech. Through the house, coming from the main t v. I have called for the last three months. I have had three different texts out to the house. It's poor man. This has only happened when they put the wireless boxes in and a new modem.  I was told that it was an error on the box, and it was fixed. I was told it was interference from a printer, a Wii,  a Xbox, a switch, a video camera for the dog, and the sound bar. Everything was unplugged. Still does it. Three guys came and put new ends on the wire. They said it was fixed. The second guy restarted the boxes and looked up something on a computer pad and said it was s error after an upload they did,  and it was fixed. The third guy came in , said it's not doing it now and said to give him a 10 on the survey. He left and when I gave him a 2 on the survey,  he actually called me upset it wasn't a 9 or 10. Its still not fixed. I called into today same issue. It took 15 min to get a person on the line. They can only give me an appointment for 7 days later. The first appointment was 10 days and the second 7 days and the third 10 days and now I have to wait another 7 days for someone to come and check some screech that only happens every few hours. They still want thematic $$$$. This is crazy. Not to mention my dog wakes up starts to cry and runs around when this screech happens. The TV has a line across the bottom when this happens.  They can't fix it. They need to fix it . If they don't this time the modem and box will be sent to them by my lawyer. I have spent more time in the last three months on the phone trying to make them fix their issue. This time they said there was an open ticket/ issue for the exact time it happened today at 1pm. We'll fix it.