@Punxsutawney Camhs have said they would be happy to write and say that DS can't talk on the phone
seriously, get every scrap of medical and professional evidence you can. IIRC you have a lot of correspondence with his secondary school which should outline a lot of his difficulties, use what you can of that to his advantage. What about primary school reports etc. did they mention communication or organisational difficulties or anything else relevant to show historic evidence?
@Natkjdcjw Do challenge the report and back that up with as much evidence as you can. Keep fighting!
Benefits and Work do a really good guide showing how to challenge the assessor's report and put your point across, but you have to join for a year, about £15 IIRC.
CAB have some very good online tips.
@LifeBeginsNow fight for what you need, it's the only way.
Generally to everyone, amass as much evidence as you can, if necessary request medical records, old school reports, anything that may lend support to your case.
DD's ATOS assessment did recognise some of her disabilities in daily living but not in mobility despite her having had a Blue Badge for several years. After a failed MR, I took DD's case to Tribunal and the Judge, Disability expert and Medical expert were all independently of the opinion DD should have had enhanced rate of both components with enough mobility points to automatically renew her Blue Badge from the outset, so I didn't have to contest anything at the Tribunal. The Judge said if the DWP had bothered to turn up, he would have made them apologise. He also set DD's award for 'It is inappropriate to fix a term' which means she will only get a very light review every 10 years, basically her disabilities are considered not likely to improve.
As above, I found the Benefits and Work guides and the CAB online guides very helpful, especially for things like keeping a diary and the observations of reliable, repeatable, in a timely manner things.
I found it an incredibly difficult process, it's also frustrating beyond belief, but each time there was a setback, I fought and fought some more for DD's future.
Never give up!