If the deposit is not refundable, the parties can call 123 15 to complain, seek help and solve the problem. 123 15 is a hotline for protecting consumers' rights and interests in China, which is specially used to receive complaints and reports from consumers. The parties may report their own situation to the relevant departments, provide relevant evidence and contract documents, seek their assistance and intervention, and safeguard their legitimate rights and interests. If negotiation with the seller or complaint through 123 15 fails to solve the problem, the parties may also consider applying for arbitration or bringing a lawsuit to the people's court according to law. Arbitration is a non-litigation dispute resolution method, and the parties can choose to submit the dispute to an arbitration institution for mediation or adjudication. If arbitration fails to resolve the dispute, the parties may bring a lawsuit to the people's court according to legal procedures and settle the dispute through court hearing.