It's your money. Go get it. You earned it. It belongs to you.
I find it interesting how our world has changed in many ways over the years - but that is an off topic subject.
One thing that has changed is how entitled consumers feel - how they think that if they do not feel like paying you the money or it just doesn't fit in their budget that they aren't going to pay you.
Write the letters, make the phone calls, but don't waste an excessive amount of time. Be stern and professional. When that does not work, take them to court - no matter who it is.
When you get your judgment, the game is not over. They have x number of days to pay. When/if they don't pay you have options.... Pay another fee and have the sheriff collect the money. If they don't pay the sheriff will confiscate their property and sell it at auction until the judgment is paid, plus fees.
Think about that....how much do you think a 50" flat screen TV goes for at a police auction? Nowhere near it's face value.
In other words, a lot of their personal belongings will be confiscated to pay the judgment.
Most don't pursue it far enough.