Incorrect pricing

Please ensure you are clear when offering the 2 +1 on suppliments as I bought 3 supplements only to discover when I go home that the 1 item was not free upon asking the stuff I was told that if an item is on sale hence the sale did not pull through, next time please either don’t run such promos during the 2+1 or do not put those items as this causes confusion in store and it’s not fair to the staff during this busy day