I think your suggestion is a good one. However, I'm not prepared to spend the time and legal fees to take them to court and I don't make empty threats.
What are you afraid of, that these guys will learn that you're capable of bluffing and then push you around? That appears to have happened already.
Though I actually agree that you shouldn't bluff a lawsuit. You should give fair warning and then file the lawsuit. What are you waiting for, someone to cheat you out of twenty thousand bucks?
You don't have to intend to sue, the debt collection agency has that option. And while the collection agency probably won't do that, they might. Never know.
