I truly understand your frustration…..
I use the same means of response that you try.
I have one advantage to you…
I’m a Scotsman living in England….. they tend to listen better when their talked at by an irate Scotsman, they do tend to be very understanding.
My sister-in-law talked to me like that once, she’s never done it again and she’s an ICU nurse….
As my old grandad used to say be firm but polite you can’t go to far wrong.