Clicks 3 for 2 doesn't apply to stickers??!!

I visited South Coast mall clicks, where I found a 3 for 2 sticker on milky bar buttons.

I was charged full price, asked them about the 3 for 2 offer because it had a sticker, they said it does not apply to this product.

Please advise why the 3 for 2 sticker was on the product if it does not qualify.

I went on to return my items, however I did want it at the 3 for 2 price.

Does the sticker not mean 3 for 2?

Are the staff well-trained?

Do they know what the sticker means?

They said the sticker does not apply to 3 for 2.

This was at clicks south coast mall, KZN.