false advertising

false advertising- pick n pay is currently running where you can purchase 2 packs of beer and get 20% off. I went to the store and bought 4 packs of beer but noted that the discount wasn’t app**** on the checkout.

when i inquired from the teller she stated that this only applies if you purchase 2 CASES of beer. my friend rang up her order , she bought 4 cases of beer but she got a discount for the beers.

how does that work? i have a pic of the special and read the T&Cs