Nedbank granted various overdraft facilities to Puricare CC, a water purification business. The appellants, members of the Dominick family, bound themselves as sureties and co-principal debtors under limited deeds of suretyship for Puricare’s indebtedness. After internal disputes among Puricare’s shareholders, Puricare instructed its debtors to pay monies into a separate 'Agri account' instead of the main overdraft account. Certain funds were transferred between accounts and, in some instances, from the Agri account to a third party’s private bank account. Puricare later defaulted, and Nedbank sued the principal debtor and the sureties. The appellants claimed they were released from their suretyships because Nedbank’s conduct—particularly its failure to apply set-off and its transfer of funds back to the Agri account—prejudiced them as sureties.