Legal analysis: the transfer fee is generally available in gyms, and 20% is not too much, but it is unreasonable without a contract signed by myself and prior notice. If you collect the evidence, transfer records and chat records you bought in class before, you can take legal channels to defend your rights.

Legal basis: Article 128 of the Civil Code of People's Republic of China (PRC). Where the law has special provisions on the protection of civil rights of minors, the elderly, the disabled, women and consumers, those provisions shall prevail.