Bad customer service

Yesterday I was at pep, store code 6459. I bought a gift bag and a R100 Hollywood voucher. Then I asked the cashier for a R200 cashback. The lady told me that she won't assist me with cashback, she would make me pay for for the giftback and make a withdrawal of R100, which will be used to pay for the Hollywood voucher. She never explained the reason for that. Her name is Sandra!!