i was screwed out of over 6 months of pay north of $50k. i wasn't keep tabs on the payments and i wasn't keeping detailed records of my work. both things i no longer let slide in any way. i spoke to many people and lawyers, but decided to move on and let it go.
in the end how much money and time and energy do you want to spend on another lousy human being or entity? it only hurts you emotionally and takes up valuable time to focus on more productive things. ten years later it's a blip in my life that forced me to learn and be better about picking clients and billing, etc. don't let the 10% ruin your work with the other 90%.