Never respond to rudeness. When people are rude to you, they reveal who they are, not who you are. Don't take it personally be silent. For more quotes and inspirations: http://www.lifehack.org/articles/communication/never-respond-rudeness.html?ref=pp
I did not happen to learn this a long time ago, only a few months ago. Give it some thought. Turns out to be true. They are not entitled and they will think what they want anyway.