PIP Capita Delay

I have been waiting for my PIP claim to be processed for 21 weeks since sending in the form after the DLA change.
I called DWP who told me it was still with Capita. That in 99% of cases a F2F is mandatory. They gave me the Capita number. Told me to chase up my claim with them!
I called Capita who told me that my claim has gone through initial assessment and due to assessment backlogs and no near assessment centre, my request for home assessment would be considered.
The person put me on hold and checked the booking system, came back to tell me that no appointments were available. I was then told that my nearest assessment centre will call me urgently, if an appointment is available. But if I don't get a call in two weeks call them back.
I have long term liver Disease, fatigue and spinal stenosis I am also suffering from anxiety and depression because of PTSD. I have provided lots of evidence, specialist reports, GP letters, scans, letters and therapy plans. I could not have done much more, following your guide carefully.
I really am stressed beyond normal range. Any guidance would be welcome.