(a)  If the agreement governing a credit card plan so provides, a credit card lender may impose, as interest, a late or delinquency charge upon any outstanding unpaid installment payments or portions of it under the plan that are in default; provided, however, that no more than one such late or delinquency charge may be imposed with respect to any single installment payment or portion of it, regardless of the period during which it remains in default; and provided further, however, that for the purpose only of the preceding provision all payments by the borrower shall be deemed to be applied to satisfaction of installment payments in the order in which they become due. Nothing contained in this section shall limit, restrict, or otherwise affect the right of a credit card lender to change the percentage rate or rates of interest applicable to the credit plan between the credit card lender and a borrower upon the occurrence of a delinquency or default or other failure of the borrower to perform in accordance with the terms of the plan.

(b)  No charges assessed by a credit card lender in accordance with this section shall be deemed void as a penalty or otherwise unenforceable under any statute or the common law.