There are people like that in the world. I don't like them, but I've learned to deal with them over time. I let them say their part without interruption. I listen or pretend to listen, especially if they are saying the same thing over and over. I 'agree' with them and go from there. It's not worth the time or energy to argue with people like that.
HOWEVER, in my younger days, I could lose my temper fairly quickly. I worked at Dairy Queen when I was 16. I remember this lady that came through the drive-thru. She was a bitch, no way around it. She was rude and very demanding. I mean come one, you're ordering a hot dog from the DQ lady. She demanded 2 hot dogs with everything on them. I filled her request, I just put extra of everything on them.
I handed them out the window with my best fuck you very much smile and closed the window. I knew she would check them because she was that way. Well, let's just say that she had a mess of hot dog toppings in her lap. She banged on the window and asked for a napkin after calling me a bitch. I handed her one of the dinky DQ napkins with a look of shock and awe and said I had no idea how that happened and closed the window again and went to the back. I was dying of laughter which almost covered up her knocking on the window and screaming. Luckily, the manager was trying to get in my pants so he thought it was funny too.