I now know which school and instructor is being referred to, and I'm 100% certain this isn't a wind-up. I haven't been there for a long time, and though I know the person concerned, I didn't know things had got that bad.
I've been talking to a friend who found himself in a similar situation. He contacted Chirp. The head of Chirp contacted the CAA at the highest level, and they paid the school an unscheduled visit. My friend's name was not mentioned. This sounds to me like the way to go with this.