I'm not doubting Buenchico's account (or legal knowledge!), just commenting that it seems unfair that people can defraud others and then be protected by the police. Surely it should only be "harassment" if the non-paying party is constantly chased for the money owed. Could I not pay back my mortgage and claim that the mortgage firm was harassing me for money when my house was repossessed? For that matter, was the paper that published those paedophiles' names sued for harassment?
Anyway, rant over. I'd be very tempted to take action along the lines that you plan myself, but do agree that you may (unfortunately) be on a sticky legal wicket. For that sort of money, if I had/could get knowledge of a couple of "heavies" in her area, I'd be tempted to take extra-legal action. (Which could, of course, backfire totally so it would remain a temptation).