unable to return sealed infant formula

On Monday, March 2nd, my mum purchased a 1.8kg tin of Lactogen Number 1, infants formula instead of Nan Number 1. We retained the receipt for exchange on the 4th only to be told that Pick n Pay Chatsworth cannot return the formula as they do not have the Nan in stock. There is no such instruction from your stores stating that there is no return or exchange on a SEALED infants formula with the receipt retained thus I am confused as to why it was a hassle to receive a refund. I do not have any names but a lady agreed for the refund after the other, *********** 'senior' staff declined it. It is absolutely unacceptable for the staff of a reputable retail store that are on the same page, wasting my time! Maybe Pick n Pay Chatsworth are running a circus there because they think that Indians are a bunch of clowns to just accept anything and walk away with the matter unresolved! Their local adverts state that they are doing their bit for Chatsworth, what exactly are they doing when they cannot process a simple refund for a senior citizen of the community???