It sounds like you have the services of the Florida Department of Revenue. The easy answer is to go into their office and request a contempt hearing as well as that they file a motion to increase payment on arrearages. If you have had their services for years and not gotten very far, you may want to hire a private family law attorney work your child support case.
Family law rules differ significantly in every state, especially procedural rules. Always seek the advice of an attorney in the state where your divorce was filed.
He probably did not get arrested because he did not have the current ability to pay. If the AGs office is too slow (they have a large case load), you can hire a private attorney. They can't take anything he does not have! Remember that