Aeronexus (Pty) Ltd, an aircraft maintenance company, rendered services to Million Air Charter Ltd under a written agreement. Million Air failed to pay amounts owing, and Aeronexus exercised liens over aircraft owned by FirstRand Bank (WesBank), retaining the logbooks. To secure release of the aircraft, the bank issued an irrevocable written guarantee in March 2004 undertaking to pay Aeronexus R1 959 240.30 upon successful conclusion of an action in respect of the liens. Aeronexus issued a simple summons against the bank in April 2004 claiming payment for services rendered and goods sold and delivered. Nearly three years later it filed a declaration relying expressly on the guarantee. The bank raised a special plea of prescription, contending that the amended claim introduced a new debt based on the guarantee which had prescribed, and that the original summons did not interrupt prescription.