BPA (the respondent) sued the appellants for outstanding diesel debt. In 2001, BPA concluded an agreement with the Albertinia Dekriet Trust for the supply of diesel to refuel the Trust's trucks. Ms Müller signed a credit application form and suretyship on behalf of the Trust. In 2003, Mr Otto of BPA approached Ms Müller to open a diesel depot on the Trust's premises to supply diesel to the Trust and the public. This required upgrading from a 9,000 litre to a 23,000 litre tank. The Trust fell into arrears, owing approximately R7 million. BPA sued the Trust (represented by trustees Mr Marais and Ms Müller) and Ms Müller personally as surety. The appellants contended that the 2003 depot agreement was a new oral agreement with Ms Müller personally trading as Albertinia Diesel Depot, not an extension of the Trust's agreement. They argued the Trust never traded in petroleum products and that Ms Müller sold the depot in October 2008. All invoices, statements, and VAT registrations continued to reference the Trust. The trial court found dissensus but applied quasi mutual assent to find the Trust liable.