PIP appointment & evidence for home visit

I was sent an appointment for PIP assessment tomorrow by letter last wednesday at a centre 40mile away so i contacted Capitas to let them know i wouldn't be able to get to it. As i wouldn't have time to get evidence to have it locked into home visits only, the chap altered note on file to be only nearest centre & said the system generated new appointment would probably give me 2 weeks to get evidence to them.

I did request a home visit on my PIP form as i have anxiety/agoraphobia but didn't realise that i needed to gather the medical evidence for this myself. I contacted my doctor today to do this and had reply that they could only state what i have told them not give a medical opinion having not witnessed this themselves (surely many diagnosis are done on patient info not always seeing symptoms in person?).
Doctor wasn't very understanding suggesting capitas would have limited home visits and surely i could go to centre, which i stated i was unable to due to distress using public transport etc ( mentioned in past appointments with her) and being forced to push myself could put my recovery back as its enough of strain going to her practice which i know and is mile from home by taxi/lift , the nearest centre is 10miles away . This letter is costing me £20 and may take 2weeks so could be that i don't have it in time anyway. Is it likely to be enough evidence?

I am going to change doctors (not found one at practice yet that is much use with mental health) but now worried how all this will effect my claim. I'm fairly sure Capitas hadn't contacted them as i only saw her last week. She wouldn't consider filling in the GP form in B&W pack said DWP would contact them if want any info so i've only been able to get a letter from my counselor (non NHS) as any form of medical evidence.

Is there anything else i can do now try to improve the situation? I didn't think i would also have to battle with my own doctor:(