KNOCK THREE TIMES?!

Hi,
For around 20+ years I had a string of psychiatrists, supportive psychotherapists, cpns, and social workers for mental health issues.
Then around 2019, I was discharged from all services . Partly this was because I felt abused by the therapist, and this made things very tricky for everyone, and secondly I am sure because of the cuts to services. Since then I have sought support and help from a number of charitable organisations for group setting support and counselling. The Commissioners for our area actually funded further psychotherapy for me privately after my discharge from the mental health trust.
I had been in receipt of PIP for many years. Then without backup from professionals who did the relevant reports for DWP, I felt pretty threatened by all that I heard about DWP's behaviour to claimants and the rhetoric coming from government, and others which was not supportive or pleasant.
Now I think it was on here that I read something about getting a unexpected visit from DWP. The pattern of visits like this was twice on one day, once on another, followed by a letter demanding attendance at a local DWP office.
Now I never answer the door to people who knock on my door, or buzz from outside our block of flats because of my anxiety levels. One of the serious aspects of my condition is very high anxiety levels and serious clinical depression. Several attempted suicides.
I have had no notification from DWP or letter so far, but the visits only happened quite recently.
I am in my mid -70s and still have severe mental health challenges. My official review should be in about three years time. I have read there is something DWP do, to collect statistics and to ensure accurate awards and they check people out, randomly This is called a Performance Measurement Review. In effect, this just seems like any DWP review - which is scary for me.
I know any face to face meeting would cause a great deal of anxiety and agitation in me and would potentially send me overboard emotionally and psychologically.
Is there anyone out there who can give me advice as to how to deal with this should the letter come telling me to go to the DWP office. I feel neither safe to go there, nor safe to have anyone here in my home.
Given my level of vulnerability, is it possible for my GP to contact the DWP stating this so that if necessary I can do a paper response, or phone response?
Thank you very much for any suggestions or information about my predicament.
Of course no letter has arrived yet, but my suspicion is that it may!
A number of people have reassured me that the mysterious visitor would not be anyone from DWP because they don’t do that, especially to over 70s or those with known severe conditions....?
So I feel somewhat reassured. But does anyone here have anything to add?

Thank you David.