How can I help my daughter?

Hello. I need some help and advice please. My daughter Deb is 26 and has autism, she was diagnosed when she was 13. She was recently detained under the mental health act and we can't get her out of the mental health unit. I've tried her GP, the police, even Citizens Advice but no one seems able to help. The longer she is in there the more distressed Deb is becoming. She's always loved imaginary play and this is the reason she was detained I think because she was acting differently, but that's just how she is. All the professionals say it is mental illness but this is just autism. But I'm worried she will become mentally sick if we can't get her out of there soon. Please help I'm at a loss of what to do to help her.