Bad service

I am not happy with the service I received today at Volksrust total sport. I went there to buy school bag for my son, the price tag was R259 and when they scan the bag is was R279 and I told them that I want the bag with R259, I was told that they don't do that I have to pay the price that the system scanned. Aybo ithini iconsumer act, they called the manager who told me the same thing, saying it's human error, ngingenaphi lapho because it's their fault not mine. Then she said she can't help because she is not there to authorize, I should come back tomorrow. I use transport to go to town and that's money and I have to go back again tomorrow. Total sport needs to have a process in place so customers are not inconvenienced just because the manager is not in.