How Do I Receive Child Support From Local Agency

I am lost in my situation. My ex owes owes me almost $30,000 in child support on 2 children. I have called my local agency because they are involved in it, and I seem to be going in loops. They won't do anything unless he goes 6 months without paying. It seems like he pays just enough to keep from going to court. He's actually been to court before off and on for about 2 years, and they dropped him. WHY I don't know. They won't tell me much when I call them, and I can't talk to my case worker unless it's an emergency. He is only ordered to pay about $315 a month on 2 children which isn't a lot considering they're both teenagers now. I can't afford an attorney so I was wondering if there was something else I could be doing. The state doesn't seem to helping.