When I was working inbound calling for customer service, I had a rude-ass custy scream at me, then at my supervisor. To be fair, it was my second day (first day had been non-stop training), and my second phone call *ever*.
I was still learning the product and offered to have her hold while I found out the answer to her detailed and very account-specific question.
As soon as she transferred to my supe, she screamed at her to "keep that fucking retard off the phone until you train her better!"
Eight years later, I was a supervisor of my own department and even THEN, I had managerial approval to NEVER take a call from her.
It was great, because I had approval to reject claims from her when they came in - although, being the better person, I only rejected them when they were blatantly wrong.