Bad customer service and attitude from PEPCell Umlazi 4935

I went to Pep Cell Umlazi Mega city on Thursday to do cashback, i bought an item of R7, the cashier Thandeka refused to give me cash back she said it compulsory to buy for R10 in order to receive cash back. She was extremely rude, I told her that I had previously bought something less R10 and received cash back but she still couldn't budge an inch. Today I tried to address the issue with the store manager Nokwanda but surprisingly she showed the same bad attutide I experienced from the cashier, this is despite the fact that I was not complaining but rather trying to find a solution, since I am a regular customer. She told me that the store doesn't gain anything from cash back and it doesn't help on their sales targets, which is absurd because I wasn't asking to be given a cash back without buying, I was only querying the mininum amount R10.