Sorry to hear that Heathrow09L, there was a time when a letter to the top person would have always got a reply, it seems that manners count for nothing these days, never mind best business practice, just one word though, given that EK is a Middle East airline you may still get a reply in another couple of months!
In your case an investigation should have been instigated and as it went from department to department, (all blaming each other!), it would have taken time, eventually, the reports all collected, someone would have had the job of doing an assessment and then writing to you, but that was in the days when things were still done properly!