Shambolic Vaccination program

I received an SMS that I must go to Dischem Head office in Midrand for my vaccine between 2:00 and 4:00 pm on the 19th July. When I got there the guard at the parking told me that I cannot go in as they are full of walk-ins. I am not sure if it is Dischem or the Dept of Health that caused this stuff up but how can walk ins have priority over people who have been sent an SMS to go in for the vaccine . Someone needs to jack up their system as it is very frustrating to drive all that way and to be turned away by your guards.