How do i get him to leave me alone !?

okay. so one of my ex-boyfriends, (aaron, not robbie) keeps i-ming me,and texting me all the time. the second i go on AIM, he i-ms me. im getting really sick of it. i have absolutly no feelings for him anymore. he is most deffinatly a manwh*re, and a player. i want him to stop contacting me. can you please help with a way thats not too mean, but not so nice. THANKSSS ! <3 :D