Insight Marketing Solutions Sent us a bogus invoice then tried mutiple times to collect Cakais Maine

Company had called and asked who is responsible for Accounting, then submitted a fake invoice for, "US Business Registry Listing" charging $379.99. Our industry has no need for this. Clearly they asked for the accounting then put their name in the invoice, however that person would not be the person responsible for purchasing, just processing and paying the invoices. They called multiple times, and finally the invoice was sent with no back up. I emailed them back and asked them not to contact us again without any back up documentation. They then proceeded to call and threaten my company with their legal department. If the red flags weren't already enough, no one resorts to intimidation having not even provided the requested back up.