Poor customer service

I was disappointed at the service we got with my sister at USave (Sebokeng Zone 14). We went there to buy bread at around 11:40 today (17/08/2022). We saw a price of R12.99 on the shelves but when we got to the till, the bread was R18.99. The cashier was already done with the transaction. I told my sister that since this bread of this brand we thought was R12.99 but now it's the same price of the other brand I preferred so let's rather take it.

We asked the cashier if we can exchange and he politely said it was okay, we should just go over that counter. Pointing where the manager was, well I believe it was him. Yes I went to fetch the bread, and my sister asked the guy if he can help us to change the bread. The guy stood up because there's a lengthy wall so we can't see him properly if he's on the chair. He stood up and with an attitude saying "why did you even pay for it", well as I was trying to explain that we saw a certain price then when we got to the tills it was a different one and we decided to take another brand of bread which will amount to the same price....he just said "put that bread behind you" and sat down. We stood there like idiots not knowing if it's okay we should leave now or not until we decided to leave. That was cold indeed.