Complaint Review: First National Card

I received a First National Card in the mail marked Urgent Approved $6500. I did not apply for this card. There is only one phone number to call and if you call it, you activate the card, which I do not want to do, especially after reading the ripoff about them on your website. Thank you for this information. Can you tell me what to do? I'm told that if you are given a credit line and don't use it, it takes points off your credit score with the credit agencies. Thank you for your website and for your help.

J.c.
Ruskin, Florida
U.S.A.