I'm expected to know that I have to make an appointment for a sonar, even though there are no notices to the effect!

I went to their Wilgeheuwel branch this afternoon for a sonar for my right foot. I was asked whether I had made an appointment. I said that I had not, because previously I was not required to do so. Seeing as it is not for an involved sonar, like for a baby, but just my foot, and seeing as there are no signs up in their reception area instructing patients to make appointments for sonars, I did not know that I had to make an appointment. I was told that they are fully booked and that they could only assist me on Monday, the 30th of January 2023. This means that I wasted my time and petrol to drive to their practice! Why do they not put up large, visible notices to inform patients that they have to make appointments for sonars? To look at me with droopy eyes as if I am stupid to not know that I have to make a prior appointment, is totally unacceptable! I was so disappointed!