Exchange of a product bought within 15 minutes

This morning at 11:14 I sent one of my employees to purchase me some Vienna’s and he happened to have purchased the wrong ones. At 11:29 I walked into pick n pay Douglasdale to exchange the eskort chicken Vienna’s for the enterprise Vienna’s and was told they don’t exchange it. I told the guy that was there that I haven’t been out for long which I only had been out for 15 minuets and the sad thing is I have a business in the same centre and I don’t even treat my customers the way the pnp staff do. I am disgusted in the service.