You need to hire a private party (investigator) to take pictures of him working and document everything. I know someone who is going through this right now. Then you confront him with the evidence. Because what he is doing will land his a55 in jail for a very, very long time. I would do a little homework and see what the penalties are for lying to the government about your employment and lying to the court and see if he really doesn't want to agree to pay more in lieu of prison.