I once worked with a narcissistic client who was telling my billing manager how we should run my practice. He would try and take up 1 hour and 30 minutes and frequently ignore boundaries. Sometimes he would send me nasty emails and all things considered he had zero empathy. I believe it is essential not to engage with them and just have one or two in your practice. Good mirroring skills are es sentail.
I am not surprised to hear this, since narcissists believe they "know best" and anyone's boundaries surely don't apply to them. It is imperative not to engage with a narcissist. They will only get angrier and will never see the error of their ways.