Yes, when things go wrong they cover up.
My aunt (who had profound intellectual disability and couldn't communicate, but was physically very healthy and lived to 60 without needing any form of medical care) was in hospital recovering from a knee replacement, and she suddenly died. Nurse casually mentioned "we kept giving her more and more of her epilepsy medication, but she just kept having seizures." My aunt did not have epilepsy! When this was pointed out, the nurse went white as a sheet. They'd clearly mixed her up with another patient who did have epilepsy.
When my mother died, her abusive ex-boyfriend pretended to be her next of kin and demanded they not resuscitate or give her any medical care by lying that she had a DNR. I can't blame them because I guess hospitals have to take on faith that someone claiming to be next of kin actually was, but when I - as her actual next of kin - tried to find out what had happened, it took six months of basically constant badgering and eventually going to the Ombudsman before PALS would even speak to me. PALS just closed ranks and refused to answer the phone or reply to emails or voicemails.
When I was young I had my (massively inflamed and cratered) tonsils removed, was sent home with a type of painkiller I was allergic to and an MRSA infection in the wound no one had noticed. Ended up having to be rushed to hospital in an ambulance so dehydrated I would have died that night if not put on a drip, where I was treated like a naughty child who had just been very lazy and naughty in refusing to drink water when I physically couldn't swallow and kept vomiting. I did everything right, went to the chemist and spoke to my GP, things started to get really bad on a Friday evening after GP and everywhere was shut, and by Sunday evening with nothing open except hospital I'd gone blind and couldn't stop vomiting tar-like stuff. If it'd been a weekday I would have called my GP, if I'd had any option at all except 999 I would have taken it! And to top it off they tried to force me to take the same painkiller, and no one even examined me, just put me on a drip. They also dumped me on the street in my pyjamas with no money or phone at 7am the next morning, and I had to get a bus and beg the bus driver to let me on for free just so I could get home. And then I had to make an emergency appointment with my GP so I could finally, finally get antibiotics to clear up the infected throat wound, since A&E didn't think there was any point looking at the throat of someone who had just had bloody throat surgery.
Even recently, I went to see a neurologist and all his questions were blatantly designed to catch me in some agenda, and nothing to do with my actual symptoms or trying to treat me. He asked me loads of intrusive and inappropriate questions about my income and whether I was on disability benefit or trying to apply for disability benefit, clearly his first thought was whether I was scamming to fake benefits; then loads of questions about my job and sick leave and how many sick notes I'd asked for (I'm the boss, I can take whatever leave I like and never need a sick note); then finally changed tack and asked if I had any history of mental illness and when I said yes he got a big self-satisfied smile and sat back and told me very confidently that I had a psychosomatic disorder and needed to be treated by a psychiatrist. No tests, not
Oh and this was following a major head injury, where I was unconscious for more than 30 minutes. That's the whole reason I was there.
Paid to see a private neurologist who was a dream and correctly diagnosed and treated within one appointment.
Sorry, that was a lot. I have had and my family have had wonderful experiences with the NHS and individual doctors and nurses too, but it's the bad ones that stick out. Not for the poor treatment so much as for the lies and failure to take responsibility.