Bad manager service

Good day

I went to OK Doornpoort to buy the special of the c***** milk. There was only loose one's on the shelve so I took it but when I came to cashier Herman the Manager said he does not sell it like that. So I asked for a return ticket and he answered " i am independent from OK and I dont give return tickets" i whic I rep**** that he is part of a group and he said he is not. He Herman made such a big scene about the milk that I was all red in the face.. how is it possible to humiliate a customer like that in front of other customers????

I need this to be sorted