What can CAD do......
Jammedstab
For starters they could actively and vigourously follow-up investigations with the foreign carriers involved in these incidents - rather than a letter sent Second Class post to some PO Box somewhere - or at least that seems to be as effective as it gets.
If the airline is Chinese then forget it - more a case of sorry for not having SIDs to your liking .....
When such requests for information fail to provide any credible response then, rather than getting tough, the process that failed to ellicit a response in the first instance is repeated again. However, the second letter appears productive so CAD is content; kidding itself that it is being proactive....