I used to work taking calls for a private health insurer.
Some highlights:
A severe storm was imminent so we were all sent home. Next day we received a complaint from a member who wanted to know why nobody was available to answer his calls. It was explained about the storm etc to which he replied that he too was sent home but didn't think such care and consideration should have been given to the likes of ourselves as we "only answered phones all day" so, presumably, we were expendable.
The woman who called in to demand to know why we declined her claim. I explained that the claim reference didn't appear to be one of ours. She said she knew that as she was with one of our competitors but, as she was waiting on hold too long, she rang us to get it sorted for her. I explained about us being different companies but was told I was talking nonsense as "You're all in the same line of work aren't you?"
The man who had his claim declined because he wasn't covered in that particular hospital. He wanted to know how he was supposed to know all that sort of thing so I explained about his policy documents and that he could have called beforehand and asked if he was covered. He replied that he had undertaken this surgical procedure on the advice of "a mate down the pub".
Then there was the never ending stream of why we didn't pay out on all manner of outpatient receipts to which the answer was we didn't cover the cost of washing machines, dishwashers, pet medicine, a three piece suite, etc amongst other things, and umpteen non-prescription items from a chemists such as buckets and spades, energy bars, hair accessories etc.