For a reno project my general contractor estimated costs and explicitly told me most of the time he over-estimates and adjusts as necessary. The plumbing estimate was $4500. The work took a total of 15 man hours to complete. The general contractor told me the plumber will not adjust the bill despite tje general contractor’s promise to adjust Over-estimates. This is an egregious over-charge. $300 an hour is twice industry market standard. I have been threatened with a mechanics lien. Any advice? Thoughts? ps: I have an email in which the plumber said he charges at $160 per hour per man. Accordingly the cost should have been $2400, not $4500.