False pricing

Yesterday i bought a cutex and mascara that was on special according to the pricing board. When i got to the till they said its not scanning like its on promo anymore. I requested to speak with the manager and she is the one who told me that theres nothing they can do when the item is not on the promo because i asking what do they do when the price on the system is different from what it is advertised on the floor. According to my knowledge as per section 23 of CPA they were suppose to give me with the advertised price. But i bought the items anyway with the system price.