False advertising

So last night I purchased a 4 pack plums at woolworths airport and it had a sticker of was R29.99 now R23.99 came by till paid with card when I got home only to see they charged me full price r30 for plums bt sticker shows r24 that's perthetic so my question is why put stuff on sale and you charge normal price that is actually day light ******* never expected that Woolworths would rip me off