Medical assessment for pip

Husbands pip form sent to dwp. Requested a home visit. Letter received today for appointment at assessment centre. Telephoned ind.ass.ser. Home visit denied due to history of violence. Paper assessment denied due to no medical evidence within 6 months except repeat prescriptions. Request they contact gp. Denied. Told do not have to request more info, that doctors don't reply and if no regular contact gp cannot say what my husband can/cannot due. Told no use rearranging appointment as husband cannot attend (due to mental health has been unable to leave the house since 2016 and as there is not enough recent evidence from professionals cannot have as assessment. If he doesnt turn up at the appointment the file will be closed. Told hands are tied by dwp. Phoned dwp. Told would contact ias to ask them to contact gp but cannot make them. Awaiting phone call from dwp on tuesday. Included with pip form were letters confirming diagnosis of progressive ms, arthritis, mental health issues, depression, skin rashes etc. Also letters with care plans, symptoms etc. And uptodate copies of prescriptions. Due to illnesses starting in 1990's/2000's some evidence is very old. Phoned gp surgery. Awaiting a call back. Any advice please. For the future i can only think of calling out our gp on a regular basis just So he has recent medical records he can produced. Although the gp can each time write down symtoms etc. As We have been told his ms is progressive and there is not anything they can do (we have it in writing in a letter) i am not sure how the gp will feel about it. And this doesnt help with the present problem of no medical records within six months except repeat prescription. Thank you barbara