McDonald's false prices

So this morning I went through McDonald's drive through in Parkrand, Van Wyk Louw Drive, to buy breakfast, and I see the South African Breakfast in big advertising costs R50, I think to myself that's reasonable. Then when I'm paying, the lady helping me says it's R53. I pointed out that it's advertised as R50, she says she's been telling 'them' to change it. I consider this false advertising because I might have chosen something else, but since I was rushing to work I paid the false price.