Section 4 of the article at http://www.ficpi.org/library/montecarlo99/damages.html discusses the legal penalty for trademark counterfeiting. To be entitled to such a penalty, the trademark owner would have to show that the accused infringer knowingly engaged in trademark counterfeiting.
From the wording of your question, it doesn't seem that you have been sued in court but rather that you have received a demand letter from a lawyer representing the trademark owner. Perhaps you can resolve the matter by explaining the facts to that lawyer. My guess is that it is more likely that you would achieve a favorable result with advice from an attorney experienced in trademark matters. You would of course have to balance off the cost of such advice against the cost of capitulating to the lawyer for the trademark owner. In considering the latter, take into account not only the direct payment they are demanding but also the potential damage to your business and personal reputation if the issue is not resolved with a comprehensive understanding of its various ramifications.
Generally everyone is the commerce is liable for copyriight and trademark infringement, no matter who actually manufactured the ifnringing products and what anyone knew or didn't know about them.
But documents that tend to support your claim that the products were genuine and from a lawful licensee under lawful license can persuade a rightsholder, as can the lack of support for the infringement being willful, and cooperating in the request for contact infromation for others in the distribution chain is a bargaining chip. Ultimately, hiring an IP litigator would most increase your chances of avoiding litigation and avoiding or reducing the fine they want you to pay.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
You don't give enough information to indicate what happened. Was the merchandise not licensed (like a shirt with a Steeler logo) or was it a fake (like a simulated Coach Purse)? What kind of "fine"? A fine is usually involved when a criminal statute is involved. If you sold counterfeit or unlicensed merchandise, you may be culpable regardless of your lack of knowledge. You need a lawyer.
Clifford L Tuttle Jr
Attorney at Law