Explain the apparent paradox that the excessive use of short-term funds could increase the risk of illiquidity for a firm

Ace Discounters buy $600 000 of invoices for a 4.3% fee. Ace collects 90% of the debts in 30 days and 10% in 61 days. If funds cost Ace 6.0% p.a. and assuming the costs of collecting the debts amount to 2% of face value per month for debts collected within 30 days and 3% of face value per month for debts collected within 2 months. Was this deal worth doing for Ace? Why? How could Ace manage a better outcome?