Merrick Bank (NextCard) They ruined my credit report. They want me to pay on credit card I never used Old Bethpage, New York

I have been charged and have had a negitative mark on my credit report. They want me to pay on a secured credit card that I never used. They told me that I can only use what I put into it. I never put anything in to it and I called and cancel it. I never received a statement afterward. a few months later I received a statement saying I owe 860.00. I called and the rep told me they can not do anything for me. I sent several letters to Merrick bank and never received a respond. Please if anyone know of a good number to call them let me know.

Ariel
Kailua, Hawaii
U.S.A.