Sorry to here that Mum is in hospital, bris, but glad she is getting 24hr care
Like you, I think I would check that the hospital is signed up and, if possible, get a print-out to have with me should I be challenged.
I think I would also contact the Chief Executive of the trust (or what ever the post title is) and remind that person that they have signed up and that they are obviously not making sure the guys at the coal face know this. It's a training issue.
I'm sure you don't want to be there 24/7 with Mum, but a bit of flexibility will help, I'm sure.
All the best