bad customer experience

i went to primrose shoprite,i got a bad bad service,the is a special that was running for 5 kg sunlight washing powder for 99.95,it end on the 12 may when i get there ,I've asked one of the staff members and she told me it was a one day special and now the 5 kg is 155 and there is nothing they can do,they way they were rude they kept laughing and talking behind my back ,I've never experience such humilliation