Changing Flights

I booked a flight for business on Kulula to depart from Lanseria at 11.20, had to be in Durban the latest 13.30. I got an sms from them stating the flight had been cancelled and they very kindly accommodated me on the 13.40 flight. How is this accommodating me? When I called the call centre, all they could say was the flight has been cancelled and you can fly a day earlier, a day later or at 06.15 in the morning. This after I clearly stated to them I was unable to get to the airport at 06.15 as I was out of town, and that my appointment was for 13.30 which by the way is earlier than I was even flying. Thanks Kulula will try never to fly with you again.