unskilled in CPA

I went to go buy my weekly cat food and took the packets of four sachets bob martin. It was advertised as R17 on both price labels in the shelf. When I got to the till it scanned R22.95 and I informed the cashier it's scanning the wrong price. She called the supervisor and he went to go check the price. He came back with the label saying it is not the same barcode. I told him both labels said R17. He insisted it's not the same label as the items I took. I then asked to see the other label as I remember there was 2. He conveniently said he tore it up since its the wrong price. I just told them to take it off the system since I didn't have time to ask for this label regardless of what he said. I think it's unfair that he did not uphold the CPA law of what is advertised is what is paid. Deeply dissatisfied and disappointed