I can certainly understand the frustration from the OP when things don't go right. This can happen with any company.
I'm from the group that doesn't like to book reservations on the internet (including dinner reservations). I ALWAYS like to talk to someone in person on the phone. So far, that has worked fine.
We like KOA's and the prices can be all over the map depending on where they are. My first search when looking for a campground is rvparkreviews.com. Depending on the review, I may skip a KOA or choose one that has a good review.
Any campground is as good as the owner. Most, if not all, KOA's are privately owned. I have found the owner's of these campgrounds want their business to thrive but there is always blip that can happen.
Safe travels,
MM.