In the UK, GP surgeries have "lists" of their patients. A new patient wishing to join a practices list must live within a clearly defined area, although some practices may allow a little leeway.
Some patients might find their home address is covered by multiple GP surgeries and so there is some choice. In some locations you might only be eligible to apply to join one surgery. If you're struck off their list you then have no GP at all.
I have heard of patients being struck off for making quite normal & reasonable requests, or making a reasonable complaint.
I have also heard people being refused when applying to surgeries on the grounds they don't take ME patients.
I have also heard someone who tried to make a complaint told the practice didn't take complaints from ME patients.
In my life I faced discrimination for my religion (one boyfriend's mother), for being a girl studying a guy's subject, when I moved country because of my nationality and then because I was a female doing a guy's job. Frankly, all water off a duck's back - I was good at my job and had no problems proving it.
I had never before experienced nor anticipated the discrimination I have faced since being diagnosed with ME. Discrimination from the ignorant who know no better is one thing because they can learn. Discrimination from the so-called educated is another and they won't learn because of an unshakeable belief they know better.