Very bad customer service

On the 19th August I bought baby formula at Pick n Pay in Strand Street. I bought 2 Isomil formula but the one was number 3 I bought it by mistake did not check properly the number, also the colours are the same and they were packed together on the isle. On Friday around 11:15 I went to Bellville store and the store manager Mr Pieter van Niekerk did not want to do the exchange. He did not even listen to what I was about to say, he just said he does not make exchanges on baby formula. I asked him where it says on the policy his response was he does not care if it's not on the policy I can contact customer care he will not do the exchange. I'm really angry as I'm writing the tone of his voice and facial expression clearly shows he does not care about client service.