A bad teacher is a real problem. Your learning is still your job. Find another way in.

Both halves of that are true at the same time, and holding only one of them is what costs you. A teacher who cannot explain things is genuinely unfair, and being right about it does not put the material in your head. The exam will not adjust for it. That is a lousy arrangement, and it is still the one you are in.

Find one other way into the subject this week: a different book, a video, the friend who gets it, someone a year above. Twenty minutes of a source that makes sense beats an hour of frustration. Keep the complaint, just do not let it be the plan.