I'm a plumbing subcontractor working on a commercial renovation on which the property owner is also the general contractor. I finished a job which also had a very large change order included- which was approved- doubling the contract amount. The pay app is already overdue for payment, and the contractor is someone whom I have worked with many times. This is common practice for him to try and re-negotiate after the work is completed, and only one payment has been made. I did file the 20 day prelim when the job started, but there is no written contract. How would you suggest I proceed- I was hoping to salvage whatever is possible to continue working with him in the future. (if even worth the effort-not afraid to file the lien if it comes to that.)