If one bribes them to remove the lien, what makes you think that they won’t be coming back for more anyway (since they’ll see their victim as an easy mark)? If the lien wasn’t justified and I had proof, I’d take the scammers to court to obtain a restraining order prohibiting them from my property and forbidding any contact or legal harassment. I’d also sue them for my time, my court costs, and my aggravation.

I suggest that you look at court records to see if those clowns have had any legal action against them for such behavior. If they have, then it might be very easy to win a case against them — why would you bother perpetuating a scam and feeding scammers?