Since a year or more has passed, what "proof" do you have that you are and were entitled to the commission? I'm not saying your aren't entitled, but the "degree" may be a subjective decision. For example - where you no longer employed by your broker when the commission was earned? If so, consult your employment agreement to find out how much of your actual earnings remain available to you for payment. Does your name appear on the purchase contract or listing agreement? Have you retained these documents? Where you a member of a local board at the time? Local boards hear commission disputes usually company to company.....but....they may have some suggestions. Also consider contacting AAR and finally the department of real estate.