Brandon Howard Six Point Entertainment Refusal and, or failure to pay engineer's fee / Internet

On March 24, 2012.  I was hired directly by Brandon Howard himself to engineer a session at Paramount in Hollywood, CA.  After the session ended at 6am, his assistant instructed me to send an invoice via email.  I submitted the invoice the next day.  I received no response or payment.

On April 4th I received a group email (intended for his fans) that the song I had worked on ("Believe in Love") had been released.  The email included a statement that the song was for a good cause and a link to the iTunes store so that fans could buy the song.  A snippet from a Wikipedia article about Trayvon Martin was also added in for good measure (formatting symbols included).

I followed up on May 1st with another email and attached invoice.  I once again received no reply.  This continued after a few more attempts.  Eventually, I began to contact his manager, Jonnie Forster, who said he'll "forward my email to Brandon".  I have heard nothing back regarding my invoice.  It is now October and, at this point, I'm assuming Brandon and his manager have no intention of paying me for my engineering services.

Please keep this in mind when working for these individuals.