We are a subcontractor and have already finished the job and received final payment from the GC. The only thing we have not gotten paid for was the very last Change order we had sent them back in November. We had already signed and sent in the Final Waiver of Lien because we thought everything was paid for. They say that (even though we already sent them our own version of a change order) we should not have done any of the work since they did not issue an approved work order before hand. Is there any way for us to get our money?