I worked as a customer assistant in the checkouts department.
Unfortunately at my store our self checkouts are faulty (and no supervisor/manager is bothered to fix them) which results in the customers experience being limited.
In order to book days off for holiday we must fill out a "holiday form". We must give in our holiday form at least 3 weeks in advance. Many of my collages and myself followed this rule however we would only receive our holiday back 3-6 weeks later! The store's explanation was that the person authorised to allocate holiday was on holiday or off sick and was not able to get back us.