Speed is not what makes credit expensive. The amount you take and the number of months you keep it decide almost everything you will eventually repay.
On a short-term credit transaction, meaning up to R8 000 repaid within six months, the National Credit Act caps every charge. Interest may not exceed 5% a month on your first such loan in a calendar year, or 3% a month on any that follow it within the same year. The once-off initiation fee is capped at R165 for the first R1 000 advanced plus 10% of the balance above that, to a ceiling of R1 050 excluding VAT. The monthly service fee may not exceed R60 excluding VAT, and credit life cover is capped at R4.50 per R1 000 outstanding.
Put numbers on it. Borrow R4 000 for three months at the ceiling and you repay roughly R5 150, so the credit has cost about R1 150. That is a great deal per rand borrowed, and a tolerable one in total, because the term is short. Take R30 000 over 24 months as ordinary unsecured credit at around 27.5% a year including fees and the instalment lands near R1 640, with roughly R39 300 repaid by the end.
Neither figure is a quotation, and your own will differ. Both illustrate the same rule: keep a fast loan small and keep it short, and the arithmetic stays on your side. Stretch either dimension and you pay for the convenience several times over.