Unfair customer service

I was @ Game Cresta mall because I received an email stating that 3 of 2litres Excella cooking oil is R60,i was there @ 8:30 ...they refused to sell to me saying it's price error..so i need to know how does their mistake have to be accounted by me..I'm not happy at all...when I left the allowed other customers to buy with that price but they told me to leave they will phone me if head office approves but they never did