Pathetic service

I bought a combo of a 7kg potatoes,7kg onions and a 1kg carrots for 99 rand at the checkout point it scanned normal price.I enquired about why aren't the price 99 rand they told me its a national error but it states on there advert its only at rondebosch on special the manager was not of help and ignored us and only the supervisor said sorry ,I ask about pick n pay policy of double the difference if the item scan the wrong price they told me it doesn't count.I waited for more than a hour and a half to get the problem rectify Pathetic service of the store