it depends on whether the customers have eaten that dish first.

if you have eaten it, you have to buy this dish with your own money. And said to the customer: sorry, because of personal negligence, I served the wrong dish, in order to express my regret that this dish is a gift.

if you haven't eaten it, you still write: I'm sorry, because of personal negligence, I served the wrong dish, so I have to withdraw it. Please forgive me and I'll send you the correct cuisine right away.

be sure to say sorry, sorry and so on. And smile.