A booked slot is not a kept slot.
Here is how the chair stays full.

1. 1
   Booked

   The booking lands in your calendar and starts the sequence.

2. 2
   7 days before

   Confirmation email with a one-click reschedule link.

3. 3
   48 hours before

   What to bring, the address, an add-to-calendar file.

4. 4
   24 hours before

   SMS: reply C to confirm or R to reschedule.

5. 5
   2 hours before

   Last SMS. A freed slot has already gone to the waitlist.

Every reminder checks that the appointment still exists before it is sent. Click the figure and the customer replies R to the 24-hour text: their slot is offered to the waitlist instead of sitting empty.