My question involves a child custody case from the State of: Illinois

I have a Visitation Order with my ex husband who has never stuck with what it says. He is supposed to have him every other weekend from 7pm Friday to 7pm Sunday. He has never picked him up on time, either he is too early or way too late between 9-11pm and the same time for drop off. I have tried talking to him especially during school season but he would bring him even later. I have called the police when he wasn't here but they said because it was a joint order they couldn't do anything nd maybe because he wasn't present during the time they arrived. Only recently I called and they did make him return my son but they didn't give me anything in writing so I could present something showing proof of what I'm saying. I don't know what to do