Who should I call to stop my sister?

She took POA on my mother while she was very sick and moved her out of her condo onto a retirement home that my mother could not afford. She sold my mother's condo and spent all the money in 3 years. My mother does not drive and did not spend money on anything. When my mother found out she was broke she wanted to revoke the POA and my sister had her committed into a senior behavior health hospital and they won't release her. My mother is locked up and my sister put me on a list who cannot visit. Now she can't even make phone calls. If she had her declared incompetent nothing can be done. My sister has tried to alienate my mother by lying to her and manipulation. She lies about my brother and I to make it look like she is the only one my mother has and threatens her that she will be all alone. She is a very greedy person! I've always known that but never thought she'd do her mother this way.