False advertising

False advertising. Purchased a sale item online but at check out was charged the full price when we spoke to someome at the store they said the item was on sale during the day yet I have screen grabs of the item showing on sale on the website that same night so I don't understand how this is a valid excuse for dischem that I could not get the item at the sale price . Does dischem put things on sale for a few hours not for a full day ? If so why was it still showing for sale on the website?