Terrible customer service

Bad Customer service that i received from Tops Spar in Empangeni they advertised R74.90 for Savanah and at the till it scanned R84.90 and the supervisor by the name of Aron refused to sell it to me with the advertised amount and he told me the system they use you can't override the price, i felt he was taking advantage and he just left me there without giving a proper info as to why i cant get it with the advertised amount