Clinic time slots?!?!?

Hi, I visited your The Glen branch yesterday for my baby's immunization at around after 3 and was informed that I will not be seen as there were already 2 people in line. Is this how your system works, because then a disclaimer should be added to your closing time slot of 16:30 for the clinic?!! I used my money and time to visit your store and this is the kind of treatment you give you customers. Unacceptable!!