In contract law, the 'part-payment problem' refers to the general rule that payment of a smaller sum does not discharge a debt of a greater amount.Which of the following is NOT an exception to this rule?
A.
Where payment is made by a third party
B.
Where there is accord and satisfaction
C.
Where the equitable doctrine of promissory estoppel applies
D.
Where both parties agree to a lower sum in full and final settlement