(1) The amount required for the full prepayment of the consumer credit contract must be no more than the sum of the following less the amount referred to in section 52:
(a) the unpaid balance at the time of the full prepayment; and
(b) if expressly authorised by the contract, the administrative costs incurred by the creditor arising from the full prepayment or a charge equal to the creditor's average administrative costs arising from full prepayments of consumer credit contracts of the appropriate class; and
(c) if expressly authorised by the contract, a fee or charge that does not exceed a reasonable estimate of the creditor's loss arising from the full prepayment.
(2) In calculating the unpaid balance, the creditor must only include interest charges and other fees and charges that have accrued or would ordinarily be payable under the consumer credit contract up to the time of the full prepayment.