Sibling POA Is Blocking Communication with Mother?

While my elder sister has never been a real sister to me since I was very young, she has not stopped short of being really mean spirited to me for years in any capacity that she could.

She holds POA for my mom; both live in Florida. My mom divorced my father and moved to Florida about 18 years ago when she retired at the age of 70. I live in Connecticut. Since my mom moved to an assisted living facility 4 years ago, my sister has done everything possible to interfere with my ability to communicate with my mom.

Examples: 1) when my mother changed rooms within the facility and was assigned a new phone number at the facility, my sister not only refused to share that information with me, but actually blocked me from getting it from the assisted living facility. I called the police and they said I have to hire an attorney. 2) When my mother fell and broke her hip bone and the artificial hip she had, the day after my mom's surgery, she went off on a cruise, leaving my mother alone. After 2 to 3 weeks of recovery Mom was transported to a therapy center to recover, my sister refused to tell me where she was sent after repeated requests and my mother telling her to communicate that to me. I had to call all the facilities in the area for 3 days to find my own mother. 3) I now have learned from my younger sister that my elder sister (POA) has not started taking my mail that I send to my mother and has not given it to her. I do not know if she will. The mail is letters to my mom from her mom over 60 years ago, which my mother has been waiting for now for 2 weeks. She has nothing like that from her mom.
While I understand she (POA) does not need to communicate things about my mother, she has successfully blocked my ability to get any information about my mom's health, send her mail, and get information if she moves to a hospital or even if her phone number changes. I can only imagine that she will now change my mom's telephone number so I cannot have access to speak with her anymore. When I visited my mom a few months ago, we tried to add my name to the assisted living facility roster so I can get even updated contact information about my mom, and even my mom has been blocked from changing this because a few years ago she was diagnosed with Alzheimer's Disease.

Please help if there are any other options without going through a very costly court battle which I cannot afford. My mom is 89 this year and is not well. She may not have another year left.
Thank you so much!