'Consumer preferences do change from time to time' HA! How would THEY know? They respond to perceived fashions, not preferences. I know dozens of people of my generation who would buy Cadbury's Cabana, Five Centres and Milk Tray Bar and I am sure lots of young people would like them too.
'It is important for Cadbury to maintain a wide range of products' WHAT? Endless variations on the chocolate/biscuit/wafer/caramel theme or dozens of various flavoured crunchy bits in CDM is wide ranging??? Dipped Flake and Twirl represent choice and variety do they??