Cant purchase products in the store

Last week I purchased some coconut covered cholate ***** from southgate Ackermans. My daughter wanted more so I went to Ackermans Signet terrace in Lenasia. After waiting for a long time in the queue with my chocs, i get to the cashier only for him (Harmony Vuma) to tell me that its not scanning so I cannot purchase it. On speaking to the manager on purchasing the items that were on the shelf, she (Siza) was rude and unhelful. She said “thats not (her) problem. I can purchase it because theres no price for it”. I have had previous unpleasant experiences with the ackermans. Their staff is rude, unhelful and have attitude problems. Furthermore , i think its very unprofessional to have items on the shelf yet tell a customer that they cant purchase it. Siza also refused to provide me her surname (she also had no name badge) and refused to provide the head office number. My daughter cried all the way home. I was extremely disappointed and will never support this store again.