Direct Merchants Bank Harrassing Phones Calls! Scottsdale, Arizona

I have been receiving several phone calls on my cell phone as of late but when I listen to the message, it's a recorded message just asking who I am and if I am listening to this message and am the person they are looking for to stay on the line.  I didn't make too much of it at first until I noticed whoever it was calling my cell phone several times a day.

Today, I received a call from someone stating they were calling from a collection agency for Direct Merchant's Bank.  They asked me if I lived in Redford, and unfortunately I did say yes (stupid, yes, I know).  They then proceeded to tell me I owed money on a Direct Merchant's Credit Card and why did I stop paying the card in 2009.

I informed the person on the phone I never even had a Direct Merchant's Credit Card and I had no idea what he was talking about.  Of course, I know it's his job to harrass, which is fine, I can handle my own, but I need help on finding out how to resolve this.  I don't owe any money to this company, I don't even know who they are.  The gentleman told me that I opened this account in 07 and stopped paying in 09, which is impossible because we had paid off our debt and bought a house in 08.  I would never have applied for this card. 

How do I resolve this with this company???  And get this off my credit report??? SOMEONE somewhere did this to me and I'm nervous. 

Any insight would be helpful.