My mom lives by the phrase "Kill them with kindness". She told me that she had a really mean coworker one time, but she was always so nice to him and he just couldn't stand it. I think it really works good, I try that with anyone that annoys me. If I were to be mean to someone, and they completley ignored it and were just plain nice to me, I would most likely not bother them anymore. So I would try that first.