Trying to find National Principle Group
The solution is simple. Ignore these fools and block the numbers. Ask your supervisor to do the same. This looks like a scam to me. As for Cease & Desist, written demands sent via CMRRR are way more effective than oral demands because it creates a paper trail which would come in handy if the violate the request and you want to sue them. But then again, these guys do not have an address, plus they may be using an offshore base/call center in India or China to run their operations.