Longwood Inc Matt Carter Unsolicited phone calls offering to assist with selling my car. Got my info from craigslist ad. Nationwide

I placed an ad on craigslist to sell my car.  Shortly afterwards, I got a voicemail from Matt Carter from Longwood Inc offering to assist with the sale of my car for a "small fee".  I did not return the call.  A couple of days later I got yet another voicemail from the same person with the same message asking to call back and that they wanted to help me sell my car for a fee.  I again did not return the call.  From what I understand, companies are NOT supposed to contact sellers on craigslist unless they are actually purchasing the item.  I reported the calls and the company to the "do not call" registry.