My biggest problem is with the attitude of the manager. I understand having a stressful day, I understand even that inside, the manager might have been annoyed at answering the same question for the umpteenth time. But I've worked in many restaurants, and in the good ones, the manager would NEVER speak to a customer like that, never try to turn an issue around onto a customer - especially one of the restaurants own making. In the well run restaurant, the manager would say something along the lines of 'I'm so sorry for the inconvenience! Can I buy your drinks for you?' Not giving away the store, not taking it personally, but with an eye towards diffusing the valid complaint and making the customer happy. Yes, even when it's busy, even when they are dealing with problems in the kitchen, and EVERY day, ALL the time - positive, calm, diffusing customer service. That's the difference between a good manager and a poor one, between a well handled customer complaint and a badly handled one.
KC