How 'shark' lenders make money when you can't pay.

Payday lenders and some credit-card products charge interest and fees so high that a small debt can balloon fast. The longer you take to repay, the more they earn, so the system is quietly built to keep you paying.

Lending to people in a tight spot is risky, so it's expensive, but it's also hugely profitable, because desperate borrowers have few options and rarely shop around. That combination attracts businesses that profit from the struggle.

A £200 shortfall can turn into hundreds more in interest and fees. Minimum payments keep the balance alive for years. Knowing how the trap is built, and what a realistic repayment actually costs, is the best defence.