I need help. I have a company North Atlanta Magazine Corp. trying to get money out of me and for the life of ,?

This company tried to sell me magazines. I had 30 days to say no thank you, yet they keep calling me and when I ask them for their email address they always give me a different one and none of them work. I do have a phone number but they will not give me their real email address. They are really harrassing me for $20.00, because I put a stop payment on the check and they put it through using a different check number. I need help. Any body out there that has any idea of how or where to get the true email address please let me know. The name is North Atlanta Magazine Corp 5175 Perfermorance Dr. Cumming GA. 30040. I have called them and asked them and they lie to me each time. Please Help. Im desperate