If the loan has been repaid but the guarantee company is unwilling to return the deposit and car keys, this is an illegal act and you can choose to call the police. Before calling the police, you can try to negotiate a settlement with the guarantee company. If negotiation fails, you can report the case to the local public security bureau and provide evidence to prove that the guarantee company is unwilling to return the deposit and car keys. When reporting a crime, you can choose to report the crime to the local police station and the police will mediate.