KFC denied me buying what I wanted.

I went to KFC in Alexandra Mall Johannesburg after work. I waited in the queue till I got to the till. I asked to buy a 21-piece bucket, and I was denied because apparently, they do not sell meat without any side. So basically, I was supposed to buy rolls and chips that I did not want in order for me to get the 21-piece bucket. How ridiculous is that? The cashier did not bother to explain why I am denied buying meat without any sides.