This question was a little difficult, but according to the plot and character setting in the novel, there were several possible methods: 1. Just tell him that you have no money and refuse to trade with him. Although this might be a little ruthless, it could directly express your attitude and not leave him any chance to cheat money. 2. Use some euphemistic words such as "You're a liar. Our trust in you has been in vain" to express your dissatisfaction and disappointment. This kind of expression was more subtle, but it could also express your attitude. If the swindler was more experienced, he might try to use some tricks to cheat money. You can hint that you don't have enough money or that you need some additional information to confirm your purchase. If he still insists on cheating you, you can take some tough measures such as asking him to provide bank account information or refusing to trade with him. No matter which method you choose, be careful not to use overly intense words to avoid hurting the other party's feelings or self-esteem.