First, there are places for driving school students. Only those who have passed the exam can continue to recruit people if there are vacancies. Therefore, under normal circumstances, coaches very much hope that students can pass. After all, when you leave, you can recruit new people and make money. So I won't keep people out of the exam.
Second, driving schools generally collect money once when they register, and generally do not add money in the future. If you don't take the exam all the time, you will always practice driving. Every time you practice driving, water, gas and venue fees will be expenses. The more you don't take the exam, the more you lose. Therefore, in one case, you will not refuse the exam.
Third, if the exam is really blocked, it may be that he wants to scare you into paying. If he really wants you to pay, you can go to the boss. You'd better look at the contract, too, to see if there is no charge for later writing.
Fourth, if the card prevents you from taking the exam and paying money, then you may have practiced too badly and failed the exam, so you should practice harder. I can't pass the exam this time, and there will be another time. I won't let you take the exam.
In fact, it is very rare that the subject 2 exam is blocked. If you do, don't bury it in your heart. It's best to ask in person. If you dare not go alone, it is ok to find someone to accompany you. Don't keep your words to yourself, maybe the coach is doing it for your own good.