If you want them to stop calling the easiest way in the world is to say..*Hold on, do I have your permission to tape this conversation*..They will drop that phone like a hot cake if they are the shady ones who want to holler and yell at you..and will not call you back..IF they are legit and don't mind, get the addy and send a drop dead letter explaining your situation, in which case a honet legit place will act accordingly.
Another favorite of mine is to act like I can not hear them and wait until they turn their ear pieces up etc. and then I blow a marine whistle.
Yep..I get calls for someone who never even lived here..

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"Cast upon this globe without physical strength or innate ideas, incapable in himself of obeying fundamental laws of this nature which call him to the supreme place in the universe, it is only in the heart of society that man can attain the pre-eminent position which is his natural destiny. Without the aide of civilization he would be one of the feeblest and least intelligent of animals.."
Jean-Marc-Gaspard Itard