Has anyone thought about pushing them into an involuntary bankruptcy. With respect too your outstanding bills you probably would not get much, if anything at all, other than some self satisfaction, but the threat of involuntary bankruptcy may be enough to force them to pay you. The bankruptcy laws changed several years ago, and I believe a new code has been enacted. Bankruptcy is not an area in which I practice, and there are people out there more knowledgeable on the subject. However, this may be something that you want to look into.

By the way if a bankrupt company offers to do business with you during their bankruptcy, take the business. Your bills become an administrative expense which are accorded a priority of payment above most secured creditors, and the bankrupt is obligated to pay its current bills in a timely manner under court supervision. This happened with a client a few years ago. His bills predating the client's bankruptcy were subject to the reorganization, and were not paid, but his current bills postdating the bankruptcy were all paid on time per court order.