why could i not get a refund for my return trip when i missed my flight to the place?

<p>I have a question.</p> <p>Can someone please explain why I could not cancel my flight back from Durban to Johannesburg at 20:05 and refund it when I missed the earlier flight at 6:15?</p> <p> </p> <p>The guy at the Kulu sales desk at Lanseria airport told me the ticket was nun refundable.</p>