What should I do if I don't want to go because the fitness instructor's certificate is to pay tuition by installments?

Negotiated settlement or civil litigation. According to the law, if negotiation fails, you can report to the Consumers Association or the industrial and commercial department. If it still can't be solved, you can file a civil lawsuit. You can also file a civil lawsuit directly without consultation. Liquidated damages refer to the money that one party should pay to the other party when it breaches the contract according to the agreement of the parties or the direct provisions of the law. The standard of liquidated damages is money, but the parties may also agree that the subject matter of liquidated damages is something other than money.