My sister has been taking care of my dad for a few years since my mom passed away in 2015. My dad gave her Power of Attorney a few months ago when he was still capable. There was an argument between them and my dad went to the bank and cancelled her Power of Attorney. He has now been diagnosed with vascular dementia and she is still continuing to do his financial statements. We have asked her for monthly statements as well as the right for me to have access to his financials as there is a trust issue. She refuses. What can I do?