How do you get a child arrangement order?

[Tailfeather]

My sister has a 2 year old DD with her ex. He is violent and abusive. They don't have an official agreement for visitation etc so he seems to think he can see his daughter whenever he wants, at any time of day or night and bombards my sister with abusive phone calls and messages and rings her door buzzer until she gives in.

How do we go about getting her some protection and getting some official arrangements in place? I think she needs protection from him and ideally supervised visits.

We would really appreciate some help of where to turn to to start.

Can anyone help? The police and social services aren't interested despite my sister ending up in hospital and despite him banging on her door at all hours. Do we have to appoint a lawyer (she has no money - works full time and pays for full time nursery, pays rent and bills, feeds and clothes her baby and ex contributes a little as and when he feels like it - he does not work). Or is there a department or charity who can help?