Legal analysis: you can write to recover the balance, that is, you can truthfully reflect your own situation and inform the other party that you have sold the prototype because of your own mistakes, and hope that the other party will come to replace it. Then, in order to make up for it, you can put forward some preferential policies, such as small gifts and extended warranty.

Legal basis: People's Republic of China (PRC) Price Law.

Article 3 State price management shall follow the principle of combining direct management with indirect control, and take three forms: government pricing, government-guided pricing and market-regulated pricing. At present, more than 95% of commodity prices in China are regulated by the market, and the price of catering industry belongs to the category of market regulation. As long as the price is reasonable, the government will generally not interfere too much.

Article 14 It is illegal to harm the legitimate rights and interests of other business operators and consumers, fabricate and disseminate information about price increases, drive up prices, drive up commodity prices too high, and cheat consumers and other business operators by using false or misleading price means.