Misleading info

Highly dissappeared in Sheet street ZA. The advertising strategy is false and misleading. I received a sms stating that they will be having a sale from the 15th September until the 19th September whereby sale items will be reduced an extra 20% off. Good I did some purchases on the 15th, went to a branch on the 18th, quite a distance, only to be told at the counter after purchasing items, that the sale is no longer applicable as "target was reached on Friday and head office has decided to cancel it" why was this not informed to customers the same way the Sms about the sale was sent?