I'm a personal trainer running my own business and hearing these type of stories always piss me off since it tends to make the business of personal training flakey. Trust me, a professional would never conduct business like that and even those that work in a gym environment should be held to higher standards than that.

First things first. Terminate your contract with this trainer. You're paying good money for professionalism, and although clients can be hurt while training, the lack of professionalism during your sessions may have been a red flag. A good trainer never does a program "on the fly". If you raise doubts about a movement or training methodology and the trainer doesn't explain or modify the movement for your ability then you have a reasonable right to question (legally) their ability to train you.

I have had many clients that have turned into good friends, but that has never allieviated the responsibility I have to provide them the professionalism they deserve, and expected when they hired me.