COVID vaccination site open for booking but unavailable for service

I made a COVID vaccination appointment for 27/08/2021 at Clicks FOREST HILL and when we got there, we were greeted with a sign saying “Clinic and sister unavailable for 27/08/2021”. I mean nobody even called to say that we should make alternate arrangements. Why is that site and date even available for booking when there’s going to be nobody rendering that service. Highly unprofessional, I will be withdrawing my support