Not easy to handle sales managers

So far, I found that handling and managing sales staff is the hardest. They 1001 questions and requests, 1 after another. I tried my best to be fair and diplomatic and it's getting much harder. I'm face with sales staff who can't work with each other but don't want to settle it face to face. I believe even if we hate each other we have to learn to work together professionally, putting aside personal issue against each other. I guess not many people can do that. I have my personal feeling towards people too but as professional, I put my personal feeling lock up in a bag and work professionally to get the job done.