Not sure what kind of contract work you do, but over here if we install machines and they don't pay, we go back and take our machines. Sometimes the po po gets involved but we always get our stuff. If it's labor, quotes get submitted and we set terms such as 25% down, 50% partial, and 25% once complete. It's probably gonna cost you more in court so it may be best to cut your loss, write a negative review about them on Google or wherever he advertises and move on.
Plants look awesome
Plants look awesome