Sale on purity but not all items shown

so after going to 3 clicks stores i have found the 2 sizes of purity advertized for R27.50 and R37.50 for 4 dont display all the normal flavors. the lamb and veggies, oats and honey and oats and banana are no where to be seen. the bigger sized bottle only have 4 varieties shown. why have a special and then limit the items you want people to buy. surely that is not fair to the customer. people are paying for the items so they deserve to be given all they ask for. i asked for 12 lamb and more options on the larger bottles but to date not one store has called me back. very decieving behaviour.