evidence. You write a complain email directly to the vice president cc to the dean of SOC. AFAIK, one Chemical Engineer lecturer was ceased to teach and replaced by the dean (or vice dean) because of giving poorly prepared lecture
You can collect evidence from informal occasions, e.g. other students who have obviously been treated unfairly, other person's opinion (from the course forum and classmate's blog), feedback from last batch student he taught etc.
Of course some kind of strategy need to be adopted to make your email persuasive (you should have learnt some similar skills in CS2301).
