Discover Magazine review: Scam, Lying, Company 1

discover enterprise
I received call offering some subscriptions and I was able to cancel all of them but two months after that call, I received an other call from discover enterprise saying that my account was in past due, I told them that I never received nothing form Discover enterprise and I didn’t want the service, but they told me that I cannot cancel the subscription because the trial period was expired two month ago and now I'm obligated to pay $39 each month per two years, even if I didn't received nothing from them in the mail. In fact I never knew anything about this company until they call me.

I tried to explain them that how can I cancel a service that I didn’t know I had and I didn’t received information about it in the mail. But they just don’t care; they have a very un-ethical way to make business.

To avoid fraudulent charges I cancel the credit card account but now I have received a collection letter what can I do? Can some one share how to resolve this problem? What could happen if I refuse to pay?