Tv flickers on and off

I’ve read some older posts about TVs flickering and seems to be the same problem I’m having. Some channels are worse than others, certain times do the day is unbearable. The sound also goes out at times. We have switched the box with another one from another room and the same things happen. Although the other room is fine which tells me it’s not the box but rather the line coming into the living room. Before I call the company and have to go through the whole troubleshooting and sending signals, did anyone have this problem and get it resolved? If so how?