Challenging behaviour in ASD adolescence

Hi, I have twin girls, both ASD and at a mainstream school, year 7. One has a statement and is getting on ok, albeit with a tremendous amount of support. The other has been refused a statement so doesn't get much support during lessons. Since starting secondary school in September her behaviour has deteriated rapidly and she has had many emotional outbursts, including pushing tables and chairs around the room and trying to flee. This has led to her being restrained which has led to her lashing out and therefore, being excluded. Although she was diagnosed with dyslexia, dyspraxia and audiotory processing disorder 4 years ago, her ASD diagnosis is quite recent and she seems to be fighting against it (her twin sister was diagnosed several years ago but the professionals were never sure if she was just copying her and so refused diagnosis!!). She knows we are fighting the local authority to try to get a statement but says she doesn't need support at school. I would be interested to hear from anyone else who has experienced similar difficulties. We have seen a clinical psychologist who said he didn't feel she needed help but we really feel she needs to see some sort of provessional to help her come to terms with her diagnosis.