My friend, you asked this question very well. This is a headache for many colleagues. In fact, the problem is also very simple. This requires you to develop a detailed method for dealing with similar problems in your daily work. The focus is on penalties and rewards. Punishment: The responsible person is the cashier. If such problems are discovered, he will be severely punished, including fines and expulsion, and he reserves the right to take legal action. If a shopping guide is involved, the handling method is the same. Rewards: Employees who make reports will be kept confidential and will receive heavy rewards after verification. Taking these two methods can act as a deterrent and increase employees' consciousness. There is also an "insurance", which is on the customer's side. Register members and make every effort to provide detailed information. Each item sold must be invoiced, and members must present proof of membership validity (i.e. membership card) while enjoying shopping discounts, sign for confirmation, and leave their phone number and membership card number. (Don’t be afraid of trouble. The troubles reported by employees are actually excuses. They are just for convenience, not for customers). At the same time, the employees and cashiers selling the goods must also sign in person. Note that it must be "in person" so that the person responsible can be found. Every day's sales slips must be collected in batches, with the exception of vouchers given to customers. If there are quality or other problems with the goods, customers must present the sales voucher before they can be accepted, and the voucher must be recycled after processing, otherwise the parties involved will be dealt with. If you do the above points, I believe your problem can be basically eliminated.

Friends, this is the method I used to help netizens in retail stores. As for your wholesale and retail sales, it is the same now. You can change it and treat wholesalers as VIP customers and retail as ordinary customers. That can be solved.