Analysis:

1. The contract signed for private courses has strong personal attributes and is not an enforceable contract; Even if the contract is marked with similar clauses such as "no card return" and "once sold, the fee will not be refunded", it should be considered invalid.

2. Private classes cannot be retired, which infringes on the legitimate rights and interests of consumers. If the goods or services provided by operators do not meet the quality requirements, consumers may return them in accordance with the provisions of the state and the agreement of the parties, or require operators to fulfill their obligations such as replacement and repair.

3. Consumers have the right to supervise the protection of goods and services and consumers' rights and interests. Consumers have the right to report and accuse violations of consumers' rights and interests, as well as illegal and dereliction of duty of state organs and their staff in protecting consumers' rights and interests, and have the right to make criticisms and suggestions on protecting consumers' rights and interests.