I have ongoing projects going at my boss' home. We would like to cut ties with the current contractor but he refuses to sign progress made waivers for the first three draws that he has received full payment for. He says that he won't sign anything until payment for two other draws is received. Those two draws are for materials that has not been received, work that we specifically did not approve and on site supervision that was not done (we have a log of who is in the residence and how long). Does the contractor have grounds to file a lien and NOT sign the progress made waivers?