Bashing on customer

I ordered a meal at your Parkrand franchise(cheese burger, medium meal with mayo). I changed when I got to the window and the manager(Nathi) came through to authorise the change and he told me how much the business will be working at a loss because they have already put in mayo in my burger instead of ketchup. Him and the lady that was working went on about it until a point where I had to apologise. I felt like it's something they should not have brought to the attention of the customer. It was quite appalling to be put in such a position where I felt compelled to apologize.