"Fox News channel" not working correctly

For several months, I have noticed that there are intermittent glitches of both audio and video on the HD channels of the Fox News Channel.  I use TiVo DVRs with CableCards from Xfinity.  All other channels are OK and do not seem to have this same problem.  The problem seemed to have stopped altogether for about 10 days, and as of yesterday has started again.  I have already had Xfinity techs come out to my house and run new coax from the pole to my house, from the box where the coax comes in from the pole to each of my TVs, and swap out the CableCards on all three of my TiVo DVRs.  The exact same problem persists on just the HD channels of Fox News Channel.  At this point, I am convinced that the problem is not on the hardware/cabling level at my house.  In the event that the problem is upstream from me (i.e. between Fox News Channel and Xfinity, or between wherever the signal emanates from at Xfinity to my house), what would be the troubleshooting process?  The intermittent glitches are infrequent (on average, once every 2 minutes or so), and as it is only on certain channels, some might think it nitpicky and worth just accepting, but at over $180/month for the service I am paying for (especially in an era where so many are cutting the cord), I would imagine that Xfinity would make an extraordinary effort to retain the remaining paying customers they do still have and ensure that their signal was flawless.