Not prepeared to help

I made a booking for my son to fly from CT on Wed 28 Oct CT to JHB. To his dismay he discovered that I booked the flight for the 27th (the day I made the booking). My error yes. But an honest error that has happened to many friends as well. The next morning when we discovered the missed flight and tried for an hour to get hold of them, the call centre supervisor was very stern/unfriendly in telling me that i should have checked before making the booking. YES I KNOW that! So the entire flight is lost for us, no booking change allowed, because we missed it. BUT, how can I not get my money back for a service that was not provided to me? We did not fly - so no service was given. Is a contract not that the client pays, and (Safair) provides a service to carry that person from A to B. That did not happen? How can I pay for something that did not happen. Yes my bad, but surely you can help clients out that made an honest error? You cannot simply assume that we willingly /purposely missed the flight, just to have to fight with the airline for re-instatement - SAfair booking ref 7Q82CY- Do you have no heart for an honest good customer that made a mistake?