24 hours before your appointment, we ask your bank to preauthorise the payment. This is in no way an immediate debit, as your account will be debited the next day of the appointment—it is rather a way of making sure that the debit can take place, to allow our professionals to work with peace of mind.
Nevertheless, some banks show these preauthorisations as debit transactions in their statements. Don't worry! If the appointment is cancelled, it will disappear from your account without any debit being made; this may take a few days, depending on who you bank with.