Overbooked flights

We booked our flight 9months ago,on arrival at the airport they told us the plane was fully booked.we lost out on 1 night accomodation in seychelles and we arrive 24 hours later than planned.this is really unprofessional and inconvenient considering my wife is expecting and we have to travel to dubai on a 10hr flight instead of the 4 hour flight initially booked. The lady assisiting us was yullander juke and she was not at all helpful.i wont be using kenya airways again and i suggest other people don't either