Woolworths mall of the south

I went there to look around and saw nice sneakers for my son under a 50%off board and when I got to the tills they were a normal price, I told them that there's a big board that says 50% off I was told I can't get them cause they are not marked.. That's clearly not my problem but I also work in retail and a customer always gets what they saw.. I'm highly disappointed alot