Rustenburg Platinum Mines Limited v Industrial Maintenance Painting Services CC

During 2002 the respondent performed work and supplied materials to the appellant in terms of agreements between them and submitted invoices, including invoices for work and materials to be supplied in the future. The appellant paid the invoices believing the amounts were due. It later discovered that part of the payments related to work not yet done or materials not yet supplied, resulting in an overpayment of R719 897.76. In June 2003 the respondent repaid part of this amount (R327 737.36) but failed to repay the balance of R392 160. The appellant sued for recovery of the balance based on unjustified enrichment (condictio indebiti). During trial, the appellant sought to amend its particulars of claim to add alternative contractual causes of action based on a tacit or oral agreement to repay the excess amount. The High Court refused the amendment on the basis that it introduced a new, prescribed debt. The appellant appealed to the Supreme Court of Appeal.

The appeal was upheld with costs. The order of the High Court was set aside and replaced with an order granting the plaintiff leave to amend its particulars of claim and directing the defendant to pay the costs of the amendment application.

The case is a leading authority on the interpretation of 'debt' in the Prescription Act and clarifies that a change or addition of a cause of action by amendment does not necessarily introduce a new debt for prescription purposes. It affirms a flexible, substance-over-form approach and has significant implications for amendments to pleadings and prescription defences in South African civil litigation.