How do you help a sister who has some type of dementia but is in denial?

My sister is able to shower, dress herself and prepare food. She struggles with managing her finances. She lived at the WestYMCA in Manhattan. I gave her the money to pay but she didn't (even though she told me she did). You are only allowed to stay 25 days then you're required to leave for 2 before you can return. This was not communicated to us when she began living there. She refused to leave. My other sister, Laura, tried to convince her to move out but was not successful. She was screaming and yelling. Police were called and she was eventually able to calm down. She left peacefully but the Y said she was not allowed back. My sister and I checked her into a hotel and now she has to leave by June 13th. The hotel's policy is that you are only allowed to spend 20 days then you're required to leave for 1 before checking back in. She does not answer my phone calls, email or text. My brother shipped her up from Florida because he was leaving the country. She was in 3 different centers in Florida and at one point was diagnosed was dementia. She went to a neurologist but walked out before seeing the Dr. We tried again at Columbia Presbyterian but again she refused to see the neurologist. For a while she lived with my sister Laura but walked out with her suitcase one day and didn't return.