Lack of Client Service

I visited the shop for my daily shopping when I got to the milk shelf I found out that 6 packs of long life house brand full cream milk is finished but they have it as single litres and they have low fat in 6 packs. I then as a client took 6 cartons went to the till to pay only to be told by the cashier that they do not allow loose one to be sold as a pack. I asked for a supervisor who came nd did not even introduce her self or explain in a professional manner and i then asked for a manager which the supervisor pointed an offices for me to go and talk to the manager. The manager on duty (Nonhlanhla Rumo) was also lacking managerial skills as she did not even introduce her self and failed to explain the reason why I can not buy the loose cartons as a 6pack and she told me it is the rule from the branch manager (Bavas V D Mescht) whom was not on duty. As a client I feel that the store doesn't know how to keep their clients happy. And their cashier, supervisor, and the manager that was on duty are all ***********, and unprofessional. I am not happy at all with their service as I could not get what I wanted to buy even when I was looking at it. I demand feedback.