James J. Welch & Co. AKA JJ Welch Refuses to pay HVAC subcontractor for work completed per agreement Salem Massachusetts

We completed the HVAC system per plans and per agreement however JJ Welch has refused to pay us the balance on our contract which is quite large. The only reason we received two small payments is because we refused to set foot on site to proceed with work until we received some money. We have jumped through hoops since day one doing everything as directed and even performed items that were above and beyond the agreement. They agreed to have the additional work performed but denied our change orders after the fact. Rather than submit payments they have sent us backcharge orders. The backcharges were severely inflated to 8+ hours when their carpenter was only there for .50 hours. Their communication in house is awful as the job super advises us to do one thing but then the project manager tells us we should have done something else and not listen to the job super. We have supplied all paperwork required, repeatedly via email and mail. We have received approvals and then proceeded with the work just for them to claim it was never approved. Finally they chose to hire an outside contractor to prepare a report on our work for which they were going to back charge us, however the company they hired prepared a poor report with missing information and yet they still refuse to pay us for our services. The readings on our original report were verified by the company they hired however they still claim it is an issue. At this point, our system is being utilized in the building in which it was installed yet they refused to pay their final bill. We are a small local contractor and have been unable to pay our vendors and engineers for this job related work since we have not been paid. This is hurting our relationship with our vendors and contractors as well as our employees and the company overall. It looks as though JJ Welch has a history of non payment to small contractors based on another rip off report as well as many other fines and lawsuits against them for not adhering to contracts and violating EPA regulations.