Does the creditor have to furnish proof that I owe less than a $1000.00 if I do not recall ever having the credit card 6 years ago?

I am not sure what you mean by correct. Debt collectors have their own procedures. You have already told the law firm that you don't think you owe the money. If they really think you owe it then either you pay it or wait and see if they sue you. If they do sue you, they have to prove that you actually owe the debt, the amount of the debt and that they have sued you within the applicable statute of limitations. Also, you should also check your credit report to see what's on it.

Yes.. According to the FEDERAL FAIR DEBT COLLECTION ACT you must respond in writing denying that you owe anything and they then have a legal duty to verify the debt. If you cannot identify the debt and do not believe you owe it, or most importantly that it might be identity fraud.. you have some options. For instance if you believe its identity fraud and you make a police report (against an unknown fraudster) they have to show you the ORIGIONAL documents for showing your signature to prove that it was you that incurred the debt (but if you knowingly make a fraudulent police report you can get in criminal trouble).

See an attorney, if it is worth your while.

If the card hasn't been used for over six years, it doesn't matter whether it was used by you or not, the debt is not collectible because the statute of limitations has expired.