Worse service ever

I went to go buy groceries today 25/03/2021 at Boxer Superstore located at Tswelopele in Tembisa. The groceries amounted to R1 341 and my mom used her card to pay the difference, and when we tried paying for the balance with cash we found that our money was not enough. So we decided to take back some of the items just to balance out the money we had, the cashier called for a void so we can return the other items, but unfortunately the supervisor told us that we need to pay the whole amount because the system won't allow us to return items. We told her that we do not have the money and she still insisted that we have to pay for items no matter what. So I decided to call my sister to send us the balance so we can resolve this matter. I am so disappointed with the way our issue was handled by the supervisor.