Negotiate a refund and record it. If there is an agreement, it depends on whether it is legal. The verbal agreement is basically illegal, and then you can consider calling the police.

By the way, you may find it troublesome and offensive to call the police, but I can tell you responsibly that the judiciary in China follows the principle of "people do not raise officials". It may not be useful for you to call the police, but it is absolutely useless not to call the police.