Hey Gileraguy,
Seems like a lot of the advice/opinions you've received here have come from people with good experience in other countries' training systems, or who for some reason seem to think you're in the UK. Nothing wrong with that, of course, but it doesn't necessarily apply to the system you're in. Training in the UK is good; but the way that flight training fits into the larger aviation picture is different - not better or worse, just fundamentally different.
In the Australian training environment, a student who has that many instructors in that amount of training time has every right to feel that things aren't right. It doesn't necessarily mean your school is milking you, but it does mean that things aren't as organised as you should expect them to be. Unless you specifically asked or agreed to be moved between instructors, then there is good benefit in consistency especially for the first 15 or so hours - say up to first or second solo.
I have a very few students who find value in working with whichever instructor is free on the day, but most students find that a few bits of stability in a stressful environment (eg. a familiar face in the aircraft) helps keep things on an even keel.
Cowboy boots would have certainly given me cause to wonder, but putting you in the 172 and then charging for it like that would have had me in the CFI's office straight away, dragging the instructor by the ear.
You are the customer - One of your rights is to choose with whom, when and how you will spend your money. If you find an instructor you like, then stick with them for a solid period of time. After 10-20 hours, do a lesson with another instructor that you are comfortable with based on interactions you've had around the flying school. If it goes ok, then stick with that instructor for a solid period of time. You'll get the benefits of consistency (know what's happening, easier communication, consistent progress), and the benefits of variety (don't end up getting your instructor's bad habits as well as their good ones, find more than one way of accomplishing each task)
Some instructors are in it for the instructing, and some are not. Some are very good indeed and some are complete rubbish. Choose carefully - it is your right and responsibility to do so.