paid full amount for a sale product

i am very disappointed and sad . i went on bash and i saw sale on maybelline beauty products . i then decided to take a screenshot and quickly went to foschini centurion mall . when i got there i showed the lady who worked there what i want from the screenshot. the lady didnt bother to tell me that the special is online not instore . she helped me to get the right colour for my skim and i paid along with few items . but when i got the house i looked at the receipt only to release i actually paid the normal price not the 30% off , i called the helpdesk because i was far from the mall and driving was not an option because now am wasting petrol.the sad part is the sale is ending today . so all i want is to be refunded the extra money i shouldnt have spent buying a product on special . clearly guys in this economy we look for sales to save money