They are actually stealing your money. Right now!...go check your wallet.
I like the Nitrox course. You pay money for someone to teach you how to breath.
If thats the course you were conned. Most nitrox courses now dont have dives so they dont teach you to breathe. They should however teach you about partial pressures, oxygen toxicity, nitrogen loading, equivalent air depths and decompression calculations. Which is a lot different to being taught how to breathe.
It blatantly should be part of AOW or even OW - I mean's it's a pretty standard part of diving these days.
Standard where? Certainly not everywhere. You can add it onto OW if you really want but what benefit does an OW diver get out of it?