Contempt and Custody Modification

My ex-husband is in contempt of our original modification. He was ordered to be responsible for 50% of medical costs that were not covered by our insurance. He has refused to pay anything towards our sons braces claiming he has already paid out what he would and that it's elective. Our original order is very vague and there are several issues that need to be addressed such as visitation, college, insurance etc. He also continues to harass me over issues that were resolved in our divorce (personal household items) There is a history of abuse against myself and the children.