Of course it's unreasonable to wait 18 hours.
I've seen this full circle - I remember as a child waiting 10 hours in the early 90s with a thumb I'd crushed in a car boot, and family friends waiting 3+ years for a hip replacement.
Then labour got a decent run at it - during which time I'd been through medical school and partway through my training as an orthopaedic surgeon - and saw people being referred with hip arthritis by their GP, being seen in clinic 10 days later, and having their hip replacement 2 weeks after that. I also saw the introduction of the 4 hour A&E waiting target (with the resources to support it) - which although not perfect almost completely eradicated issues like the ones in this thread.
Since labour left power, 26,000 of the UKs 180,000 hospital beds have been defunded and taken away, with little additional investment in community care or preventative medicine, and people wonder why the system is clogged up and failing, if I wasn't so cynical, I'd suggest it was incompetence...
I'm not saying vote labour, but, If you're concerned about stories like this happening to you, or your loved ones, you need to vote not-Tory at the next election if it's not too late by then.