(1) In addition to the continuation of the sales finance charge or loan finance charge on a delinquent installment with respect to a nonprecomputed consumer credit sale or consumer loan, refinancing or consolidation, repayable in installments, the parties may contract for a delinquency charge on any installment not paid in full within ten days after its scheduled due date of five percent of the unpaid amount of the installment, not to exceed $30.
(2) A delinquency charge under subsection (1) of this section may be collected only once on an installment however long it remains in default. A delinquency charge may be collected at the time it accrues or at any time thereafter.
(3) No delinquency charge may be collected on an installment which is paid in full within ten days after its scheduled or deferred installment due date, even though an earlier maturing installment or a delinquency or deferral charge on an earlier installment may not have been paid in full. For purposes of this subsection, payments shall be applied first to current installments, then to delinquent installments and then to delinquency and other charges.