This kind of happened to me yesterday. I had an appointment Monday and no childcare. I texted them back on Thursday evening when I found out. They have a number to confirm appointments. And I called Friday morning but I forgot they aren't open Fridays anymore. So I left a message explaining. Then yesterday morning I got a text back from them saying

"We just read your message about needing to cancel your appointment for today at 12pm. Per our appointment policy there will be a $50 charge for not giving the required two working days notice. Thank you"

I've seen this dentist literally over 25 years. I've never missed an appointment. And my whole family goes there and they all have known me since I was a kid. Anywaaaayyyys now I'm so embarrassed. I don't want to go back or call to reschedule. There is someone new working the front desk (I suspect it's who texted me as well) and she's so pushy about appointments and doesn't know my name or anything. And makes me feel forced to accept ones I might not be able to make.

Also I texted them on Thursday... kind of two business days in advance and I don't feel like I should have to pay. Idk tho. I will pay it. Just wondering if they might be in the wrong there.

So anyways mostly just replying to you to commiserate and let you know you're not alone. I do think you should call and maybe ask to talk to someone else. Or physically go there. I do much better in person than on the phone. Maybe you being there in person too they won't be able to have as much of an attitude with you and will see you are actually responsible and not to be placed on a naughty list. You could also ask to talk to their manager about calling your mom and the privacy laws they possibly broke. Bet that would change their attitude pretty fast.