Is this legal? Magazine Ad Contract?

[just me]

I have a small business and advertised in a local magazine. At the time I was told I could cancel at anytime and later found out it was a 1 year contract. Sales rep had a laptop and had me sign it. I didn't get a copy of the contract until I called the company a few months later and had them fax me a copy. So, I stuck it out for a year and now that the contract is over I get a new bill for another monthly charge, a higher dollar amount than I was paying before. They claim that the contract "automatically renews" at the end of the year unless I call and cancel. Is there such a thing? and is it legal? Why make me sign for a year then?