Wayne County Friend of the Court Ripping me off Detroit, Michigan

I am 55 and my daughter is 35. I was in a disabling accident back in 1986 when my daughter was 9. I filed for social security and 3 years later I finally got it. My ex-wife received 3 years of back support from social security as well but didn't report it to Wayne Count friend of the court. So, I was told 9 years ago I owed over $7,000.00 and my social security started getting garnished. I called Friend of the court and they told me that of the $600.00 a year they take from me a whole $200.00 of that is applied to the principle.
 I sent in documentation and a request that I got from friend of the court over a year ago asking that I not be forced to pay any more. I have not heard from them since.
 I believe this is so ridiculous. And I am really ticked to not have heard from them since except periodic mailings telling me how much I "still" owe them.