It is possible to block certain days or half days so that no arrangements for making an appointment can be scheduled.
For this you need to create an extra "virtual" user to enter closing days (full or half days) of the bodyshop by scheduling an absence for this virtual user. This ensures that customers cannot book appointments for those specific dates. To set this up you can go to Administration - Organisation - Personnel. Click on "new" here to create a new user.
First name = identical name of the location for which the Self Service Portal has been activated
Last name (important that it is exactly the same) = SSPAbsenceConfig
You should also link a weekly schedule to this user. If you now plan a holiday for this user, for example, on 15/08/20 (public holiday), customers cannot make appointments for this day.