If you can't admit your mistake, the shop should close as soon as possible.
The teacher who gave this question has rusted his head! This kind of school does not graduate!
Back to the topic, if this problem really arises:
As you said, this guest has certain wealth and evidence. In fact, he doesn't need to take advantage of petty gain. What he needs is a face. If you give him enough face, you can seize the customer's network with him.
Therefore, we must admit our mistakes. The general manager can't come forward, but the manager of the food and beverage department must come forward, as well as the management such as the manager on duty and the chef!
That's free, not just this meal. Also need to provide a period of free meals and a set of housing for a period of time!