Is it ethical to give a final exam after the professor has quit before teaching the remaining chapters of the course?
Remember Hanlon’s Razor: "Never attribute to malice that which is adequately explained by stupidity."

I doubt that any of the staff at the university are deliberately trying to make you fail so that they can make more money by forcing you to redo the course; it’s much more likely that someone just put things off, failed to read their emails, or something similar because they were busy with other things.

Complain to the student ombudsman at your university if you feel like a failure by the staff to properly follow procedures has disadvantaged you.