Having got a bit fed up with the 'learn, then dump' mentality of people trying to cram in their theory exams at my RF and then going off to learn to fly in the USA, I'm now charging the CAA rate for any exam taken by anyone who is not learning to fly at the Club. However, if they do learn to fly at the Club, then they will pay nothing for any exams taken.
However, if anyone fails an exam twice then we won't let them take a third attempt until they've attended a professional groundschool session in that subject......