Abused PhD candidate

As a dissertation editor hired by a PhD candidate who is being emotionally abused by her adviser, I've been googling "grad-student abuse" to find out more about this sickness. I'm appalled how little is being exposed about this, and almost nothing that's recent. It appears to me that this adviser is sabotaging the grad student's work in order to keep her under her thumb as long as possible. This adviser is isolating the student in order to emotionally abuse her, keeping her on the phone all hours of the day and night. She's even ordered the student not to have contact with me. I've APA-edited the paper perfectly and the adviser continues to undo my work and revert to previous versions randomly, so no one knows what's in it anymore. All the while insisting that the student have it done YESTERDAY... The student is about to have a breakdown and it seems there's nothing I can do to help her, since she needs that lunatic's signature in order to submit her paper. How do students keep from murdering their advisers who are certifiably insane?