Inefficient airline

I booked a flight for 18h30 with kulula.com and arrived at the airport only to find out at check in that my flight was delayed until 20h35. I received no texts informing me of this beforehand. After waiting in the airport, I boarded the plane and prepared for departure, only to find out that texts were sent to only some passengers stating an incorrect time of 22h00 for departure, so the passengers had to wait in the plane for a further one and a half hours as we were waiting for 4 passengers to arrive. The pilot informed us that this was a system error. We departed at 21h35 as the passengers arrived early and were able to board at that time. This was my first time flying with kulula.com and I'd heard that they were really reliable until that point. Very disappointed.