Complaint Review: Great Lakes Circulation

Had a door to door salesperson come by tonight and offer some magazines so they could go on a trip and earn a scholarship. Very charming person and very kind which seemed to overwhelm my usual wary nature.
After she left,however, I got that sick feeling that many others here describe and remembered some reports of magazine scams. I checked the company out and found numerous complaints all over. I canceled my check, which I am thinking was the wrong thing to do as several people have described the hell that is collections.
My question is, if I send in the cancelation form (assuming it actually goes to a real address) what will I have to wory about in regards to cancelation? Are they going to destroy my credit?

Jt
blank, Illinois
U.S.A.