Try this .... Send him an email from a new address (create a temp google or yahoo one if need be). In that email let him know that your patience is at an end, and if the matter is not resolved quickly, you will be contacting an old friend who happens to work for the IRS. Don't go into details, just say you have decided to do this because at least you will know that he will never treat another customer like he treated you, after dealing with them.
Even if all his business is on the up and up, the thought of an IRS audit will probably give him many sleepless nights ... but I'd bet he's not reporting a lot of that extra rep work, which will make him even more nervous.
If you actually happen to have contacts in the IRS, even better (trust me, a visit from a RevCan ... I mean IRS official is even more effective than breaking limbs).