Company has sent us the call to action on its letterhead (no refno. it

We have received a letter from one of the companies (textual content on the company letterhead signed by the CEO of the company ) citing that we have tried to bribe their employees to get some confidential information from their firm. The firm had sent physical copy to our office address - which we didn't receive. After a week, the same firm emailed us the scanned copy of the same letter - we have not replied to that yet. They are seeking an explanation for whom are we working for? In actual, we had approached multiple individuals working in the industry over phone and email. We requested them to give a general consultation on the industry in the capacity of individual freelance. And one of the professionals might have escalated the same thing with the firm. Pls note none of them had consulted us. We have written clearly that we need understanding at the industry level and not for company.