Absolute appalling service from Airfrance

My sister was due to fly back to Switzerland today on checking she discovered her flight was delayed,it was delayed 3 times with very little assistance.She eventually got a flight to OR Tambo International airport upon arriving she missed her exchange flight to her next destination.When she went to the desk they told her they can't get her on the next flight because someone changed her flights online today,yet she presented them with her boarding pass.If that is not enough they have now informed her they have lost her luggage.She is now stranded on OR Tambo until 11pm as she is on standby for the next flight with no guarantee that she will be booked on the flight.