Constant DVR Recording Issues

I'm constantly having issues with my DVR recordings. They're pixelated and the picture is not in sync with the audio. This only happens on DVR recordings. Live TV and on-demand are just fine. I have tried to work with Xfinity but it's nearly impossible to accomplish anything. There's been endless refreshes and updates completed and even a tech sent. There's been useless help including yesterday when they disconnected on me five times and the one time yesterday that  I thought we were getting somewhere the agent proceeded to tell me that the only way they could resolve the problem was if I upgraded my TV package and got on a cell phone plan. I'm very frustrated at this point because this has been going on around a year.