We had this recently, DD is on medication that needed a review so they text my phone and asked us to call
I called and said my DD needs a medication review. She had turned 16 5 days before.
The desk dragon got all snotty and said "I'm not authorised to speak to you, and I will be making a note of this unauthorised call".
I told her the text was sent to my phone and that DD was at school.
When DD rang with me there, the same dragon offered phone call appointments during school hours and got very cross when DD said they couldn't do these until after 4pm.
Then the dragon demanded to do them on what was the first day of her exams and said DD was being difficult.
At that point, DD, having never had to call anything official before, put it on speakerphone, and said "look, speak to my mum, this is ridiculous, I'm not being awkward or difficult, I just can't make those times."
So she says "why can't you just be excused if your phone rings in school as it's medical "
DD said "because during the time you've said they may phone, I will be in the middle of my GCSE Media exam and I'm pretty sure it's against the rules to leave the exam to take a phone call, especially when phones and smart watches are banned from the exam hall, and sorry, I'm not willing to fail all my exams over a call about medication."
The woman hung up and later DD was sent an appointment time for half term instead.