RV parks do not honor advertised rate when booking?

As long as the policy is clearly stated in writing, they have a right to then change the rates on an advanced reservation. We have not experienced this and one campground that we go to for a holiday weekend where without a reservation a year in advance, the place is booked, they substantially raised their rates last year and when we arrived with our reservation they charged the older rate that the reservation was made at. This is good business and they keep their customers coming back.