Bad service by Catherne, so named supervisor at Pick 'n Pay Fleurdal Bloemfontei

I went to Pick "n Pay Fleurdal Bloemfontein, where I shop everyday to buy a case of 330ml Castle cans. In the cold room were only a lot of 6 packs, not in a box. I took 4 of them to the cashier and ask her that I am surely entitled to get this 4 six packs for the price of a case. She asked me: why I didn't take a case instead of 4 x 6 packs. I've answered her that there are no boxes in the cold room. She called the packer and ask him to get a box. He returned and told the cashier that he can't find a box. The cashier told the packer to call 219 to ask a supervisor to come and assist. The so named supervisor "Catherine" came into the bottle store with a attitude. After the cashier explained my complaint to the so named cashier, she told me that the guy who is working with the boxes, is off today and that there is nothing that she can do for me. I've told her that I am not happy with her answer and going to pay for the 4 x 6 packs, but I am not happy with her explanation. If Catherine was in my service, I would have demote her to a packer, even worse!! Why must I pay more, if Pick 'n Pay can't provide a box? Thanks Catherine for your super bad service.