If you pay only the minimum payments, overall this equates to making more repayments. By more repayments, I mean that you pay the full amount of repayment installments necessary (e.g. $12 a week for 12 weeks), as opposed to paying less repayments when paying over the minimum amount (e.g. $24 a week for 12 weeks). This high frequency of repayments creates more installments to charge interest on, increasing the total cost. Hope this makes sense!