A trash box provider (hauling for broken concrete) is threatening to place a lien on my property, claiming that they haven't been paid for their service, despite our contractor paying and the provider having already taken the trash box (would not have taken the box if they haven't been paid). They claimed that there was cardboard boxes in the trash, and that there was an additional charge since cardboard is not allowed in the box. Our contractor agreed to pay and asked for a receipt from the dump site for charges so that he can reimburse. The provider refused to provide and decided escalate to a mechanic's lien. We reached out to try to find out what's going on but they refuse to talk to the owner (both via phone call and by certified mail). The only tripping point we have is that my contractor failed to receive a receipt for payment, but as mentioned before the provider would not have taken the trash box without payment for their service. What is my recourse here? Is this a fraudulent lien?