Kit Kat cash and carry

At Kit Kat today i went to buy some groceries holding my promotion catalogue that started on the Thursday 20 february2020 till sunday 31 march 2020 after i picked things that i come for to the store the prices were increased and they refuse to give me with the promotion price they playing with customers and the manager by the name of Usman he refuses to come out and sort the matter...some consumer are from far only to get the poor service like that