Pathetic Service from managers

I went to the store on Thursday and bought reusable Ice Cubes. Unfortunately they were not priced or barcoded. The cashier called manager on duty to assist. I waited for almost 20 minutes eventually he requested my contact details for the update regarding the item and he promise to give me discount for the inconvenience caused as I indicated that I want them. Weekend went by with no call from the Manager. On Monday 4th I was around the complex so I went in to collect my stuff. The cashier who helped me on Thursday was on duty but a different manager. Upon my enquiry I was informed that the specific manager went on leave without a handover of my item. I then waited another 30 minutes while the present manager is checking with other stores.At the end of long wasted time I received my items and he gave me discount. No apologies for the inconvenience caused it was just a silent transaction. I am extremely disappointed and felt disrespected about the service rendered. My precious time was wasted, no respect for customers especially from managers. Are they actually trained on how to handle a difficult transaction? Are they empowered to make a decision? Why should I do return visit to get an item which is not priced? Who's responsibility is that staff or customer? Where are my rights as a customer? I am extremely disappointed and will never again set my foot in that store where Managers are pathetic. I just wonder how they handle junior staff while they are pathetic on what they do. I therefore demand apology for the poor service rendered.