Spar Mount Edgecombe - False Advertising

I had chosen to purchase four Astros Cadbury slabs from Spar Mount Edgecombe, Durban. However, I was told while waiting to pay that the chocolate brand does not qualify for a discount. Even though the Spar Rewards Promotion only advertises an exclusion for Bubbly slab variants. I was told I cannot get the chocolate at the advertised price and as it will not go through on their system. Utterly embarrassing to be standing in line to pay and to be given terms and conditions that is contrary to what has been advertised.