Trouble with Ex's Communication

Hi Everyone! This is my first time on such a forum and I am writing on behalf of my boyfriend. He's been split from his ex fiance for about 2 years and has a beautiful 3 year old daughter. He's been working to pay child support and loves this little girl with his life. The only problem is the ex. She wouldn't let him see his daughter for a year and just now started letting him see her again. However, she makes it extremely difficult to contact her for meeting times and plans.

Is there someone he can talk to to make the ex cooperate? Because if she's serving him with OAG papers and has a court date pending and he's doing all the cooperating but she's not doing anything, can anything be done? All he wants is effective communication so he can see his daughter. For example, he'll call or text his ex all day and sometimes she responds hours and hours later or not at all but if he were to miss a call or text, she uses his daughter against him.

Is there anything that can be done? It isn't fair and I fear he's reaching his breaking point... I'd appreciate any feedback!