Salesman kickback problem

Payment methods can be standardized. Guests must give the money to the finance department or the front desk. If you need to pay back the money, you must give the card number and name of the guest, and remit the returned amount to the guest card by remittance. If it is inconvenient, the finance department and the sales department can send some money to the guests. As long as this method is executed once, the salesman's behavior will converge a lot in the future.