"Mismanaged Administration"

I need a simple blood test as an annual review and a PSA test. The last 2 appointments made were cancelled when I arrived at the surgery. The last one 22nd June 22, I received a NHS text confirming the appt the previous day, then a text cancelling the appointment about 20 mins after the appointment, then a further text after that confirming the appointment. The receptionist was unable to book a new appointment due to non availability and said she would advise an appointment date later. I heard nothing more and called 3 weeks later only to be told the same thing no capacity to take a blood sample which can be done by HCA and no forward booking capacity. I'm considered by the NHS as vulnerable patient having had a splenectomy and 2 episodes of Cancer treated with Chemo, radiotherapy and surgery and being 69 years old. I don't understand why the surgery can't be honest and say they no longer have the capacity to provide healthcare for me so that I can make my own arrangements, rather than keep wasting my valuable time?