Yeah anyone who has to deal with people daily know this all too well. It isn't like you are yelling at the CEO who made the issue you are dealing with. It isn't like 99% of the time the staff didn't try to make things right. I'v found you get a lot further by being nice. "Let me check on that for you I'm sorry you are having this issue." "Oh thank you so much I know it isn't your fault you guys really do a great job thanks for taking a look I hate to be a bother" THOSE are the ones who get what they want 99% of the time!