Need to get rid of someone?

This fatar$e from school keeps being interested in me and I don't know how to tell him to f**k off nicely. Because I am a nice person usually I just don't like to be bothered and unless it's the one I want (which is either dead or non existed lol) I do NOT want a boyfriend. He just called me and started saying why I avoid him, that I have a nice voice and he thinks I'm pretty. I'm utterly repulsed by him and I need a way to make him understand that without bothering too much. I'm in a difficult and tiring situation these weeks too. Help please? =/