In our case we were use to having cable at the particular campground for years and then the conversion. We were very disappointed in the now needed setup as it didn't work for us. To me stating you have cable is one thing, not being able to use it anymore is another and needless to say very disappointing from the consumers point of view. The fact they just blew us off because we were one of the few who couldn't use the setup, then refusing an adjustment in our daily rate sealed the deal for us in never returning. Of course all this was told to us after they ran our credit card. This was the KOA in Petoskey MI.
Perhaps letting people know about needing this converter box and possibly it might not work for some would be appropriate on your web site letting people know what they can expect. Just blaming the cable company is too easy. At least tell people before you take their money.