What to do about a POA who won't communicate with family?

I have a dysfunctional family (sister is a nut and married to a nut) and, because of that, my parents appointed their rather new attorney at main POA and their accountant as Financial POA. The only thing my name is on is Medical Care Proxy. It is creating problems for me now that my father has died. My mother has some dementia and is in an Indpt/Assisted Living facility. Her dementia is not bad....she knows what's going on, just repeats herself alot. She has LTC insurance and they recently denied her claim for in- home health care assistants, claiming they weren't "licensned." Meanwhile, they have paid similar claims for other residents at the same facility, using the same aides. I want to file an appeal, and I felt an appeal coming from her POA would hold more weight than submitting it myself. I have contacted attorney several times, both by email and phone (of course, he is always "out of the office.") This has been going on for a month. No replies. I sent to his office all the info he will need to file an appeal; no response. He is getting paid quarterly to "monitor" my deceased father's estate! Now I'm wondering just exactly what he is (or is not) doing. Can I get rid of him? Or am stuck? The financial POA is fine; he does communicate with me when I need his advice. I feel like my parents have put me in a "no power" position because of my sister, and now I am having trouble trying to get my mother help when she needs it. Can I fire the durable power of attorney? If my mother tries to do it, will they say she is not in her right mind because of dementia? I can't consult nutty sister; haven't talked to her since my father died 5 years ago. Thanks in advance for any help.