After my father died and when the dust had settled a bit, I did make a complaint to the hospital where they failed to diagnose two infections and allowed him to fall twice, the second time resulting in a fractured hip that required surgery. This was basically a terminal event as he never fully recovered from the surgery and died slowly over the next few months.
They replied that they were starting an investigation and would get back to me by a certain date, which, to my amazement, they did! There do seem to have been some good results, including changes of policies and the employment of a nurse whose job is to go round the hospital checking on the strategies for falls prevention and also providing training and recommending equipment. So....a result!
I do not know whether to start the process in my local hospital, where I received very poor treatment for a broken foot - not only did they miss one of the two fracture, but that fracture is malunited and I still cannot walk without crutches after year. The fact that I was in plaster for 17 weeks has caused all manner of problems, including the joint that is now misaligned. I am to have surgery in a specialist orthopaedic unit some miles away from my home.
The original hospital's foot specialist could not even see the second fracture at all! - I have been shown this fracture on the scans and it is perfectly clear. The biggest problem was that none of the doctors would listen to me - when I said it was so painful to walk I was told that it was "just where the plaster had been." I knew this was rubbish, but could not get anyone to listen.