If he has a coach qualification certificate, but you have evidence, first call the Consumers Association to defend his rights and submit evidence of their cheating, and then the Consumers Association will help you defend your rights. When you call the Consumers Association for help, you should also record the call to prevent them from answering the phone and then calling the police. Take the evidence recorded by yourself and ask the police for help. Liar, the police will take care of it. Before calling, I suggest you confront them with the evidence you have saved.
If they don't refund your money, call the police or call the consumer association to defend their rights. If you want them to pay more, take them to court and sue them. You have evidence to prove what you are afraid of, and the judge is fair. If you have no evidence, it may be difficult. The police can't help you, the Consumers Association can't help you, and the lawsuit may not be won, so the evidence is very important. Be calm when you are cheated, and don't lose your sense of proportion. If you are too nervous, it is easy to make a lot of mistakes, so we must solve the problem rationally.