I'm a General Contractor in NC. I helped another Contractor on a job for Case Farms, I had given him an estimate for the job, it was for building two temporary walls. The owner then ask us to build a third wall. When the other Contractor presented the bill the owners representative said they had an estimate from another Contractor for less money so that's all he would pay. The other estimate was for the two walls. I'm not in the habit of being told what I'd get paid after work is completed. Can I file a lien as a sub contractor?