How does one send a correction note for errors in international challenges?

I've just answered a question about the number of terminals at Heathrow airport in London. the "correct" answer given was four, but, of course there are now five

I thought of sending a direct note to the quizsetter, Bridget3, but she does not appear to be active (certainly no new quizzes for years)

You could try that, or an editor may see it and fix it. The wonderful people even fix quizzes themselves if they see that nothing has been done to respond to a correction note. They will either see the correction note, or even see it here if you post the details. I'd advise a note and patience. If all else fails a polite PM to an editor may help, but they do lead their own lives and I don't think that that will be necessary. Give it time and hopefully the problem will be fixed.

The best way is to send a correction note, not a direct message. When you send a correction note, the quiz is flagged for an editor's attention, and we'll be able to see whether the quizwriter has fixed the problem -- and take appropriate action if they haven't. This often means fixing the quiz ourselves if the author has been gone for a while.

Although we can see direct messages, it's only if we go looking for them -- and with tens of thousands of quizzes online, that isn't really practical!

CellarDoor
Editor (Religion, Music, Humanities)

But, my point is that instaquizzes do not give an option of reporting corrections; nor do they give the name of the original quiz.

So, what's to be done?