Did not receive my discount

I went to Clicks Paarl where the Eucerin Dermopurifyer wa 50% off but when I paid I was told that it's not all the Dermopurifyer products but there is a board that Cleary says 50% off. The sales lady even told the manager that it is on all that product but she manager insisted that it was not. I am very disappointed, I have been using Eucerin for many years.