I am a subcontractor working on a large commercial project in NYC. I finished my work on the job last month but haven't gotten paid. After sending a letter from levelset regarding payment, the client sent me a NOTICE OF DEFAULT AND DEMAND FOR PAYMENT stating that our CHANGE ORDERS BILLED WITHOUT ENTITLEMENT even though it was discussed signed and approved by all parties at the time. Would like to have some understanding of how to proceed with this. Thank you Serge