The respondents were trustees of the Kon Leech Trust. The Trust paid R4,125 million to ABSA Bank (appellant) pursuant to a second agreement concluded on 7 October 1993. This agreement was part of a complex property transaction involving the consolidation and subdivision of land and financing for a development called Needwood Village. Under clause 9.2 of the second agreement, the amount was to be paid by the Trust to ABSA in "full and final settlement" of ABSA's claim against the Trust in case number 11257/1993. The respondents subsequently instituted action claiming R2,425 million (later amended to R1,762,931) on the basis that this portion was paid in the mistaken belief that it was owing, when in fact, due to the in duplum rule, it was not owed. The in duplum rule provides that interest ceases to run when unpaid interest equals the outstanding capital. The original loan under the first agreement (7 October 1987) was R850,000. Evidence showed that there had been discussions about consolidation of various debts into one account. The trustees disputed the amount owing but agreed to pay R4,125 million to secure advantages under the second agreement.