My first idea would be to send certified letters to the company and a separate one to the owner as it sounds like he/she may be in a different local.  If that is not the case I would still send 2 seperate certified mailings, include a letter requesting payment sitting the attached invoices and stating your intentions should payment not be made immediately.  Make sure to keep track of the fees because I would add all fees used to pursue to an invoice and attach along with the above. 

I would most definitely report him/her to any bar associations he/she belongs to.  There is a chance he/she belongs to the local city bar and a state bar - both.  They frown on dead beats so it may help.  I would also state these intentions in the cert. letter as that did work for someone else.  The mere threat of reporting got that examiner a check in the mail.

While it may not do much good I would also report to the Better Bus. Bureaus just to make me feel better that I put the public on notice of the non payers.  I have friends that always check the BBB but I know other that don't and think it is a joke. 

They have committed theft so, while your at it check with your local small claims court to see if there are any avenues to pursue there.  Being such a big number (at least for me) it might be worth it and I think small claims can award damages or at least court costs to you too - don't quote me on that as I am not an attorney.

I know there has been some discussion about reporting these dead beats to the underwriter as well.  You may look in to that altho I haven't heard much feed back on it.

Lastly, depending on the abuse they dished out you may be able to turn them into the phone company as it is against the law to abuse someone over the phone, especially if they curse at you.  I can't quite locate it now but I have had to use it in the past so unless something changed in 6 years they could loose there phone access.  How funny would that be.....if only you would have paid I wouldn't have had your phone taken away....hahahahahahahahaha

Good Luck!!!!