I canceled my reservation, but they asked me to pay a penalty.

I was also recommended fat grafting at a nose specialty hospital, but
 since it was my first consultation, I didn't know anything and just made an appointment.
 However, I was shocked to hear that it was fat grafting at a nose specialty hospital, and
 seeing that fat grafting was done at the same hospital as the nose,
 fat grafting is effective even if you feel like your nose has changed. I had no idea,
 so I said I would just cancel, but
 they said they would refund me 50,000 won minus a 10% penalty.
 I had a consultation on a Saturday and the surgery date was set just a week before.
 Since it was just a reservation without saying there would be a penalty if I canceled, they
 only paid 10% of the surgery fee today. I said I'll pay and leave, so I paid and came back.
 They didn't tell me in advance that there would be a penalty, and it's so unfair.