ESA WCA change of assessment centre

I phoned the Assessment service (Maximus) to change my appointment for ESA WCA centre to somewhere closer to my home as they wanted me to travel 20 miles and walk down many corridors of a hospital to get to the assessment room. No chance as I cant even walk indoors without pain. I have requested that they book someone closer (I found on their website) and that it is accessible with no stairs and to also confirm that they are aware I requested audio recording. I was told there are no appointments available at the requested centre yet but I would be placed on a waiting list and would hear in due course. I was then given a phone number to call to confirm the audio recording request? I questioned what this was for as the last WCA I had I didn't need to do this. I was told that this was so the procedures and policies could be read to me and when WCA comes through I will just need to sign to say I know these things. I have now phoned the number they gave me twice and been told both times that the colleague who deals with this is very busy but will call me back. Not happened yet!! I may be being a bit cynical but I trust them not. Im thinking I should write 2 letters... one to Maximus to confirm my phone call to them and what was said and also one to DWP to let them know what is going on. I find this more stressful than the job I got medically dismissed from because it made my conditions worse.
P.S Thank you benefits and work for being here for us. Bless you. Joolz.