Dobsonville bad service and attitude towards customers

I would like to lodge a complain of one of the tellers at Food *****s Market Dobsonville Mall. Yesterday i went with my aunt to buy bread and at the door we noticed there was a special on sweet Potato for R29.99 and we took it. When paying i pay for the bread and my aunt pays for the sweet potato and the lady assisting her took the sweet potato and scanned it and then added 2 plastic bags as my aunt requested. When paying my aunt the asked her how much and she tell her fourty something then my aunt asked her why and she told her that the sweet potato is R39.99 then my told her no its not and asked me to verify with the lady and she refused to listen to what we saying and told my aunt she must come show her where she saw the price of R29.99, after looking at the price she then sees that my aunt was correct but with no apologies she continues asking other people and leaving my aunt there standing. Then my aunt tells her that she is wasting her time and she must come and give her back her money cause she already took the R100 mu aunt was paying with it did not bother her even when back at the till she was very rood to me and my aunt cause i told her not to give back the money and sell us the sweet potato and she wanted to explain that she already did it on the R39.99 price and she cant change it. I don't know if this was our fault that the store does not put correct prices or update their system. No manager came to assist and no supervisor was called to assist in this matter all we had was a teller who refused to give her name,talks bad to customers and with a i do not care attitude. We all deserve respect and one should see their error and apologize and not shout at customers and not care if they live satisfied. The till slip does not have names and its hard for one to lodge a complain. Good service should be rendered to all customers no matter how much u spending in the shop. I have a till slip to prove my case and i can point out the lady since i don't have her name it was yesterday around past 5 pm and the till number was number 6.