HGTV, HGTV Magazine Invoiced for magazine subscription that was never ordered or wanted Harlan IA

I have sent multiple letters to HGTV indicating that I have no interest in their magazine and that I never ordered anything from them.  I continue to get bills in the mail, however.  I just received the first issue of their HGTV Magazine in the mail today, even though I had notified them over a month previously that I had no interest in the magazine and that I had no plan to pay the bill.  There are no phone numbers provided or email addresses on the invoice and I have been unable to find any way to discuss this with them.