Stella I also so sorry to hear this has happened.
I think some sort of pressure group to keep this issue in the face of adoption agencies/local and country and voluntary groups, and government would be good.
Does such an organisation exist?
Just to give the other side of the coin (because it does exist), our son had fabulous foster care and we are still in touch with foster caters 3 years later.
The post adoption care we have received drom our county council adoption services has been excellent.
We have had Theraplay, a specific kind of play therapy, which has cut our ds's emotional outbursts by about a half.
I think the spotlight needs to go positively on counties/local authorities/voluntary agencies that do well. Promoting good ones/good practice - best practice always. And when children do not get best practice this needs to be seen as issue of severe concern.
There should be legal sanctions for agencies and individuals who fail children and of course to those who neglect/abuse children or allow that abuse.
I think getting a local MP interested in this topic, and willing to support, may be a way to get help.
Is your dd legally adopted by you now?
If you feel support may be withheld can you not finalise the adoption until you have the help you need?
If your dd is legally adopted could you sue for some sort of settlement to be used to provide on-going support?
I have no experience of this and I have no idea if this is wise
However, I very much feel when professions make mistakes they should be made to do all they can to rectify them.
I don't like being part of a litigious society but I do feel when people are paid to do a job, this type of (I don't know what to call it - gross misconduct) should carry some sanctions and the employer should be responsible for not ensuring the service was provided properly.
I hate to talk in these clinical terms, when it is about a child, but I think of course you need to do what is right for dd to secure her help and bring to account those who have hurt her and allowed her to be hurt.

I am so sorry for your dear child and for you. I wish you all the best and hope you will get the help your dd needs, long term.