Shoprite Horror

I went to buy a washing powder at Shoprite 120 End street in Johannesburg. The price on display was R34.99 for a 2kg Surf and when I got to the till the cashier said it's R42.99. I told her that the price on display is R34.99 she called the supervisor. That woman told me that the price tag was not there yesterday and she started swearing at me in front of all the customers in store. I told her I won't pay R42.99. She told how that I'm disrespectful I should take my things and move away from the till and wait for a manager. The manager came to assist me with no greeting or apology.