Ya, I don't get all that other gibberish.
It's like making an appointment at the garage to get your summer tires put on and you get there and the mechanic has a broken arm and says that they can't change the tires, but they can change you oil (pun intended).
You say, I don't want my oil changed, I want the tires put on. The mechanic says, well I can't do that, but you still owe me for my time.
It's BS no matter what if it's known before the appointment.
On the other hand, I've been in that situation and was advised beforehand, which I very much appreciated.
I even had it happen one time during (yes, to avoid the gibberish, it can arrive unexpectedly simply due to sex). It was obviously just one of those times. She felt horrible, but what can you do. It wasn't intentional, so all good even if unpleasant. Some times you just have to laugh at the timing in life.