It is not a KOA issue. KOAs are franchises, or essentially individually owned businesses. So there is likely no contractural requirement of the new business owner to honor promises of the previous owner. No different than John Doe selling his XYZ RV Resort to Jim Smith. Would be a nice gesture but not an obligation.
I stay at whatever RV park fits my needs, including KOA. And have never had any issue with a KOA, including the price of the ones I stayed at. The prices at those were entirely reasonable for what they offered.