Actually, we get very few annoying customers where I work, in the optical department of a major department store. We're lucky that way. People generally don't have a lot of complaints about their glasses/contact lenses, and we weed out problems beforehand by checking the glasses with a lensometer before we dispense them to the customer.  However....

tonight, I was working alone, no optician on duty, just me, covering the last four hours of the day, when in walked Mr. X., who had broken the temple [the fancy name for the arm of a pair of glasses] off his glasses. He wanted it repaired while he waited, he wanted it done NOW, he wanted both temples replaced, he wanted it done for free, and he was not polite when he was telling me what he wanted. Now I'm not an optician. I can put screws back in if they've fallen out, or lenses back in, tighten screws, replace nosepads, etc., anything that falls under minor repairs, but it's illegal for me to adjust glasses, and I have no clue how to put a badly broken pair of glasses back together, even if I were licensed to repair them. I explained to Mr. X that the opticians had gone home for the day, that I couldn't repair them, that the opticians would be back in at 9 a.m. Saturday [this was 7 p.m. Friday], and that it would take at least an hour to repair, and that as he wasn't a customer of our store, that there would be a fee as it would take the optician at least an hour to put back together again. 

Of course, Mr. X. went ballistic. He was wearing a pair of glasses that he could obviously see out of, so I am not quite sure why he could not wait the 14 hours until an optician got in - and I am not sure why he decided to blow up at me, making comments about my general uselessness and how he was going to find a different optician. As he wasn't a customer of ours in the first place I can't see that this will be a problem, and I told him that we did not wish to have him as a customer if he was going to yell at staff members. People are not used to being told that a store does not want their business and it unhinges them, they stare at you all funny as they back out of the store, still yelling or muttering or whatever they do when completely sideswiped. 

Other than the joys of Mr. X. it was a decent evening's work. After he left I got out Lysol wipes and disinfected the store - I wish he had still been there - as he seemed to be a giant germ himself I am sure that Lysol wipes would have taken him out nicely.