Threatened at Pick n pay

Last week Thursday I together with my friend went to get a few things at pick n pay in Alberton. I then noticed that there was a special when you buy 4 coke light cans you get 2 free. I checked the price for 4 coke light cans it was R29,49 and I took the can with the impression that was the price I would pay. I got to the till and found out its R10 more so I asked to see the manager to query this. He looked at my friend and I with annoyance and rudely asked what we wanted. When I was about to explain a white gentleman came to ask for assistance, he immediately stopped me from talked and attended to the gentleman. He then attended us and I explained, he told us it was not his problem and there was nothing he can do. I asked to see his superior and she came. She also told us that there is nothing she can do and we us go and report this to IBA (we have no idea what this is). My friend asked if there was nothing that could be done and she said no. The first person then told us that he wants to work and we are interrupting him. I told him that's not how to treat customers and then reminded him that he helped that gentleman before us without even requesting for permission. He further said that we must watch our step when we talk to him, I got very upset and asked him if he was threatening us in which the other lady intervened. She took my friends number and said she will get in contact with us and that was last week so now I'm writing this. After this its Facebook.