TV Service Interruption

We have had the TV package using the Contour box for five years now. We have had issues with TV channel reception for over a year. When watching a TV channel (not streaming service) the picture will often freeze for a second, than reset. Or the sound will go out, the screen freezes, and then either resets of goes black. I've tried to fix the issue by doing a hard reset for the box and the modem. No change. 

We've had tech support over the phone and in person several times. The last was two days ago. The tech said that there was nothing wrong with the signal coming into the house nor signal going to the Contour box. I told him that all our other connected devices work perfectly. He said his only option is the replace the Contour box. I told him I had just replaced it in mid November. 

He replaced the Contour box with another out of the box. After he left, a few hours later the problem showed up again. 

It's really frustrating. We pay good money for the TV service and yet connect receive consistently good TV service. If there was another option in our area for TV service, I'd seriously consider changing. 

Anyone else have a problem like this? Any moderator have any suggestions that the phone and in person Cox techs haven't tried?