I have just verbally contracted a Yid to repair major roof leaks.
He removed tiles around the house; focused more on other jobs and didn’t return to close numerous gaps in the tiles allowing rain to enter the house for six days.
Am I permitted to threaten him that if he doesn’t pay for water damages, I will report his negligence to the government authorities who could deregister him as a builder.
Although it is forbidden (under most circumstances) to threaten a person with court action, it is permitted to threaten a contractor with reporting him to government authorities.
This is because the authorities in this case are not considered arca’os (secular courts), but are rather similar to workers’ guilds, which are legitimate in regulating a particular profession.
Sources: See Choshen Mishpat 388:8, 34:20 (concerning threatning to take to court); concerning workers’ guilds, see Choshen Mishpat 231:27-28.