Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Multiple SEO companies claiming I have a past-due invoice
Reading stuff like this makes me want to go into the debt collection business. Just send letters to random people demanding money. Sounds like an easy way to make a living. What's your name and address? Just kidding. If they are sending stuff to a Virginia PO Box, close the box with no forwarding address and consider it case closed. If they are targetting you personally in New Hampshire, the best thing to do is to sue proactively before it goes to collection. New Hampshire has strict anti-debt-collection laws. Basically, what you do is go to small claims court and fill out a one-page form. Sue them for $2000, $3000 or whatever is convenient. Do not hire a lawyer. You can do this in 2 hours of your own time. Your grounds are: (1) Violation of the creditor of NH FDCA laws. According to the laws the creditor has to put all kinds of specific stuff in their threat letters. Since they are not doing this, they have violated NH FDCA. Read the FDCA so you know which specific items they are violating. (2) Extortion. Since you do not owe them any money, demanding money from you is extortion which is both criminally and civilly actionable. You sue them for mental anguish due to extortion.  The validity of your claims is irrelevant. You just need to get them in court. There are two possibilities: (A) They fail to show up. In this case you win and they owe you $3000 or whatever. Not only that if they later try to collect from you send a copy of the judgement to the credit bureau or collector or whatever and that is proof you owe them no money. (B) They hire some stooge local lawyer who appears. Accept the court's offer for arbitration. When you go into arbitration with the lawyer tell him you will drop the lawsuit if they send you a check for $500 and a hand-written guarantee from him that you will never hear from his client again. Either way, you come out ahead. By the way, it is absolutely guaranteed that the enemy lawyer will accept your offer in (B) above because the SEO company is already paying him $5000 to show up to answer your lawsuit, and the lawyer does not want to hang around all morning in court waiting for the case to be heard. If he can get out of there in half an hour for only $500 he will do it. -------------------------------UPDATE If all you are getting is calls and the caller refuses to identify themself, then it is definitely an illegal scam. It is illegal in New Hampshire to make collection calls and refuse to full identify who is calling. The phone company has methods for dealing with illegal calls. First you have to file a police report. Then you call Verizon Security at 1-800-518-5507 (or whatever your phone company is). They will trace the call and identify the caller. They you can make a criminal complaint in their jurisdiction unless the call is from Pakistan or something.