The worst customer service by shoprite

I went to shoprite to shop and I asked for cashback of R600. The cashier told me She doesn't have money and I should try other tills. I told her I won't go to each and every till in shoprite asking for money. I then asked for her manager, when the manager was called she shouted from across the store there isn't any money without even knowing or asking what was the reason for her being called. The cashier politely called her and she came and she asked her to explain why there isn't any money. The manager explained that since the morning until 1'o'clock in the afternoon they haven't made any money. All customers have been using their cards to make a payment. This is such a lie, and I don't understand why would a big store like shoprite offer services of flashback and do not have any money to give back. It was also unbelievable that a whole of shoprite didn't make a mere R600 cash since 8 or 9am in the morning. This service is unacceptable and it's such an insult to my intelligence. The manager wasn't even intrested to know how much I needed. This is poor customer service and it makes me so sickened and annoyed by shoprite.