Remember, the 'customer' is always right. [=never argue with a customer]
He is one tough/tricky 'customer'. [=he is a tough/tricky person]
The company has good/poor 'customer' service.
(..) And he didn't want to give it to me. - And it was like a whole thing. - Uh, uh, uhh! Hi. Uh, I'm the manager. And Mr. Kelly is one of our preferred customers. It's so wonderful to see you here again this evening. Right. My good man. Now I'm gonna want the milk steak boiled over hard... (..)2009 TvShow: It's Always Sunny in Philadelphia Title: The Waitress Is Getting Married Season: 5 Episode 5