TKO SPORT ADVERTISING / Scam

In Feburary 2008 I recieved a phone to see if i was instrested to advertise in a local school, I told the gentlemen to give me all the information in paper or email form. Next thing you know I'm recieving a bill 10 months later for $324.50 from a collection agency... I have been trying to get of hold of someone for few days and no responce...