Price error customer must pay

Hi, I received a just for you offer 2*2Lt clicks bubbly at R25, I screenshot the offer so my husband could purchase, but at till he never get at that price was told error it was supposed to be 25% off, I went to store to show them I loaded offer when it was 2 for 25 I want it at that price cos it was offered, I even showed them a slip that a colleague purchased the very same and price was adjusted, if they advertised it we must get it at that price