Flight change after cancelled by mistake

Hi Hellopeter

I have book flight with kulula and find out that I had swap destination with from departure. I then asked a person who helped me to check how much is it gonna cost to swap the routes. The price was too high and then I asked for cancellation. I recently found out that kulula doesn't give back refund and then i asked them to at least allow me to change the routes of which they say they can't as well. Can you please assist ?