This is the nature of the global private school system I'm afraid. I wonder if the KDHA reached some sort of compromise with regards to capping of yearly fees increases. Our experience of unregulated Asian private schools is 10-20% fees increase each year. At least we don't suffer that...yet.
However and fortunately (so it seems), we moved our kids from DSO last year. having found a not for profit school which is much more suitable for us in all aspects (except the location!).