Cadbury Special

I purchased 2 Cadbury Bubbly 150g chocolates today as there was a sign stating '2 for R 35 150g Cadbury Chocolates (excludes Wholenut, Fruit and Nut and Bournville)' and when I got my slip I saw I was being charged the normal price. When I asked about the special they went off to the chocolates aisle and came back and said that it doesn't apply to this one and I should buy a Top Deck instead. I told them that that is not what the sign says, it doesn't state anything about excluding the Bubbly. So I told them to just remove it and then I had to go to the front and fill in my details and waste my time just to get my money back for something that was falsely advertised.