No exchange and refund given

My brother had bought me a wrong tin of formula (lactogen) when he came out i advised him its wrong and went back within about half hour to exchange it as we was still in the mall. The first lady at help desk advised she doesn't know how to exchange products and i must walk with her to find out somewhere. Then another lady comes by help desk and she asks her to which she rep**** she would help me but was having a laughing conversation with another customer leaving me to stand there and wait. When she was done She refused to exchange the milk advising its in the cpa however your website advises nothing about exchanges to baby products. I advised her i cannot give my baby this milk and i have to buy a new tin to which the lady advised me to leave the milk powder there by her and buy a new one i want. She says its sealed its fine but they will not exchange it that if a baby gets sick then its a problem. Besides pic n pay doesn't even have the nan i need. Nobody explained further detail of this act. Im a regular customer there but will never go back. I rather shop elsewhere