What is the returns policy at checkers

I bought some light bulbs from Greenstone store, that don’t fit my light fixtures. I already have some that fit. I returned the bulbs to Eastgate, in original packaging, with the original till slip and person at customer service called the Michael, supervisor, I think. He told me my purchase is 3 days old and was bought at a different branch, Greenstone, therefore I can’t get a refund only an exchange. Over and over again I asked for the returns policy so I’m aware what expected of me as a customer. He couldn’t provide this nor direct me to where I can find it, must be because he’s in the wrong. This is utterly unacceptable and he needs to be taken to task on this. Why do retailers in SA think this kind of behavior is acceptable? It is clear he’s wrong but insists on telling me about the purchase being 3 days old and from a different branch as if that means anything. It’s sickening