Missed connecting flight due ro delay- not their problem

Missed our connecting flight from Jhb to Dbn because of a delay in Abu Dhabi and they say its not their problem because the connection was with another airline. Had to spend the night in Jhb at our own expense because there were no more flights & we were travelling with kids. Ground staff have a pathetic attitude and refused to help in any way. Wont be using this airline again.