False adverti*****t which led to bad service

Shoprite umphakhathi mall in Randfontein Mohlakeng false advertises products. There is a special on going currently for Nivea 400ml tub and bottle assorted lotion. I selected the firming lotion seeing it was on the same rack as the other Nivea and the promotion paper was listed. When I got to the till was told it was excluding the firming lotion and was told I could not get it at the promotional price. This led me too loose trust in shoprite as they advertising a promotion however say another thing. Spoke to a lady by the name Teboho Thulane who advised the branch manager advised that the product cannot be given to me on promotion and it was a mistake. How does a big company like shoprite make such mistakes and could not even rectify it and accept their mistake.