Why do orthodontists say they'll take ur braces off when they don't?

I feel like they BS with me and make my teeth crooked on purpose or just don't care and I've had them for over 2 and a half years. They said they'd take them off next appointment which is next month but they never did. Help? And I've had plenty of friends who had orthodontists do this to them like theyll say they would take them off next time but they don't or they make your teeth crooked on purpose. I wanna know why? Because my orthodontist is mean and pisses me off a lot.