Basic Child Visitation and Communication rights?

Me Ex-Fiance and I had a huge court battle over our children when we split two years ago. The ultimate resolution was that we signed a Joint Stipulation which stated she could take the kids to MO and that I would get the basics, pay CS, and get summer visitation. Well she hasn't allowed me my summer visitation in two years and now even wont allow me basic communication and such. She's at the point now where she says if I keep calling trying to contact the kids she will prosecute me for harrasment and have a resraining order placed on me. Aren't I automatically granted some basic rights, such as contacting my kids and whatnot, and furthermore what can I do to FORCE her to follow the court order to allow me visitation. I've called EVERYONE and no one will give me this ever precious "legal advice". I even called the cops to ask what constitutes harassment, so that i don't step over the line and they wouldn't even tell me. Please, someone help me, all I want is to be in my kids lives and be a father to them.