A contractor put a stop payment on a check which had been deposited the same day. He called a day before with leaking issues that we sent a technician to look at and determined that it was not our problem with the storefront leaking. We installed by our shop submittals that were approved by the architect. We billed via a AIA App and also signed a conditional waiver upon check being issued. Is it legal for them to stop payment and should I file a lien.