GSCM Collection Department scam, say I owe $39.97 for some Green Coffee Bean Max pills, messing up my credit Carson City Nevada

I received a call from someone in August  claiming I had won a lot of free products, The Green Coffee Bean Max being one of them. I politely informed the caller that I did not want the products but they insisted on mailing them anyway. Once I received the products I was told to call if I was not interested in purchasing anymore of the products so that my account would be canceled. I did what I was instructed but in February And March I was sent a letter in the mail from GSCM Collection department claiming to be an urgent debt collection notice. I was instructed to pay $39.97 online, by phone, or by mail before a certain date or my name would be turned over to collections. I called the company And they claimed that I never canceled my account for the Green Coffee Bean Max And that I had to pay off the debt if I did not want to be turned over to collections. I made that payment And everything was supposed to be canceled from that point. However, I just received a notice again in the mail today saying that I had to pay the same amount before 7/7/14 or I will have a collection fee of $59.97. I read online that this is indeed a scam. I need help so that my credit will not be destroyed.