Child support Enforcement Will not uphold their own court rulings jefferson city , Missouri

My child support had fallen way behind because of incarseration for years so instead of it being modified to what the law clearly states is an exceptable amount, They let it run at 1050 dollars a month for 14 years. While i was incarcerated i again and again tried to get it modified to a reasonable amount but always was told i had to do it in person.So this went on until i finally served my sentence . I got out became a productive member of society.
 
My wife and myself battled in court for two years spent thousand of dollars getting it all straightened out. December of 2011 we finally came to an agreement. They put me on probation again for 5 year because of non payment for being locked up. We pay every month ,never missed a payment sine our agreement, our agreement was signed by a judge and the child support enforcement prosecuting attorney in the courtroom .

Now i just received notice that they are going to garnish my entire check plus i have to get insurance thru my work which i already carry insurance on the kids thru the wife's work. So they want 92% of my entire check. They want me to go back to my old ways when i was young it seems. I'm at a lose here,i have to go by the law but they can do anything they want. Completely ignore a court ruling from a seated judge . What to do