Is having this new card for specials worth it

I'm disappointed in their savings card. I went on their website and saw the cardholders can get 2 x 2L Pepsi @ R30. To play safe I took a screen shot. I then went to buy it at the Sitari Checkers in Somerset West but got charged R17.99 each. When I question them, and showed the screen shot, they kept saying that special is not in Sitari. When the branch manager looked at the screen shot he mentioned it is regarding the stores in the north. So.....cardholders will not get the same specials??? This is confusing and I need an explanation.