Disappointed

I recently bought a lamb pack with a 30% discount sticker. When I got home and checked my slip, I realised the 30% had not been discounted. So I sent my daughter into the store with the slip and a picture of the 30% discount sticker. She was informed that the people working at the meat section were new and had made a mistake. I bought the meat because I needed that discount. I don't understand why I have to be punished for the mistake of staff members who made a mistake. I am really disappointed and cannot believe that a manager would even have the audacity to inform a customer that her staff did not know what hey were doing!!! That is lack of respect for customers. Clearly the poor guys were not properly trained - now I have to bear the brunt of their mistake. I was misled into thinking that that lamb pack was discounted - but it was all a show!