Collect evidence. If negotiation fails, it can be solved through legal channels with the support of evidence. You can directly bring a lawsuit to the people's court for the behavior of arrears, and you need to apply to the court for a payment order with the purchase and sale contract signed by both parties. Article 224 of the Civil Procedure Law of the People's Republic of China, legally effective civil judgments and rulings, as well as the property part of criminal judgments and rulings, shall be executed by the people's court of first instance or the people's court where the property is executed at the same level as the people's court of first instance. Other legal documents stipulated by law to be executed by the people's court shall be executed by the people's court in the place where the person subjected to execution has his domicile or where the property subjected to execution is located.