expired stock on shelf

I was at the bank to withdraw some money,, was feeling thirsty and for a snack,, poped into clicks next.. Bought a water and a whippy choclate,, payed and was leaving the store I open my choclate, took a bite and spat it out as it did not taste the way it should,, check the date it was expired on the 9/08/15. Took it back to the store,, they found about 10 more,, they changed it and I left.. That was after 2 on 21/08/15..