Clicks Pharmacy Edgmead

I had an appointment with the clinic sister for Monday 19th of April, to get my flu vaccination done. I booked online and received my confirmation email to say that my booking was successful. Sunday the 18th of April I received 3 reminder sms’s about my appointment on the next day, when I got there at Clicks one of the staff members told me that the clinic sister isn’t in on Mondays and that I should come back another day? I feel this is VERY unprofessional and time wasting. Why make online booking available on Mondays and why send me reminder sms’s about my appointment the next day? I was then told to come just whenever I want to? How is this possible? What is the reason for making the appointments then?