pip going to appeal

Hi my son who is 21 has epilepsy, autism, ADD, learning difficulties, OCD and severe anxiety has had his care part of pip refused. In 2016 after his last face to face he was awarded high rate care and low rate mobility for an ongoing period, we applied for high rate mobility as he has to be driven and accompanied everywhere he goes this includes a voluntary placement which unfortunately is 20 miles away which results in myself having to drive there and back twice in a day this obviously incurs extra costs which is affecting us greatly, because of my caring role and also having to be his driver whilst he was in education and also being a carer for my father I had to give up my work with vulnerable children and become a mid day supervisor as it was the only thing that would fit in.
After mandatory reconsideration he was awarded low rate mobility getting 10 points because of severe anxiety and difficulties getting around. The DWP has ignored the consultants letters the GP's letters and also his social workers letters. I have applied for an appeal and have been told that the letters for the date of the appeal are taking 38 weeks before they arrive and then the date for the appeal will be after that. My son is in receipt of ESA for the non working group and also direct payments which the rules of using and also finding a PA make it difficult to be of any use to him.   All this is causing us a great deal of stress my husband works overseas every two to three weeks for two weeks at a time, I am also supporting my father who is eighty and very ill. 
I have boxes and boxes of evidence is there any point in sending all of it to the court as i have sent what i thought was relevant to the DWP as i did before but they obviously feel that in the two years since my sons last face to face he has been miraculously cured!
I would welcome any help as really struggling to get any help and starting to worry about the future for our son should anything happen to us.