Price was wrong

I went to Woolies today to buy the 4 liter sunflower oil as was on promotion for 144.99 and when u get to the shelf it says 159.99 I ask the cashier how much is this she calls the manager and the manager and her the went to the till point the manager spoke with the cashier after scanning the oil without even greeting me as a customer and talk so low that I must not understand and after that she says the cashier says to me is 144.99 I was not happy as the price was wrong on the shelf and the manager self didn’t her promotion and as I understand the policy of Woolies I was supposed to get that oil for free I have proof for floor price and the service was bad