An acknowledgement in writing by a creditor, or by any person authorised by the creditor in writing, of the receipt of a part of the creditor’s debt in satisfaction of the whole debt operates as a discharge of the debt.

This section applies despite anything to the contrary in any rule of law.

If relief in respect of any payment that has been made under mistake is sought in any court (whether in civil proceedings or by way of defence, set-off, counterclaim, or otherwise) and that relief could be granted if the mistake were wholly one of fact, that relief must not be denied by reason only that the mistake is one of law, whether or not it is in any degree also one of fact.

Nothing in this section enables relief to be given in respect of any payment made at a time when the law required, or allowed, or was commonly understood to require or allow, the payment to be made or enforced, by reason only that the law was subsequently changed or shown not to have been as it was commonly understood to have been at the time of the payment.

Relief, whether under section 74A or in equity or otherwise, in respect of any payment made under mistake, whether of law or of fact, must be denied wholly or in part if the person from whom relief is sought received the payment in good faith and has so altered his or her position in reliance on the validity of the payment that in the opinion of the court, having regard to all possible implications in respect of other persons, it is inequitable to grant relief, or to grant relief in full, as the case may be.