smart shopper savings club they sent me a letter in the mail on 10/31/2011 saaying that i got a 100$ target gift card voucher and that i had payment methods of 60 for $19.98 for usings thier website, it says on the letter that indianapolis, Indiana

I got a call about two weeks ago from a lady for a free 100$ target girft card voucher just pay &6.90 for s&h. She also signed me up a 10day risk free trial to a website called thesmartshoppersavings.com.
I got a letter in the mail on 10/31/2011 for the girft card and website. The websites letter says that after 15 days of receiving the letter i will start being billed $19.98.
60 payments of $19.98.
I tried to call the number on the letter and it just rings then says its invalid, I dont want the risk free trial anymore, nor the payments to start.
At the end of the letter it says: sincerly, stacy jones, director
Ive been to the website and dont know what to do or how to cancel.