Thanks for your question, I've moved it here to forum feedback as it's a question for beyondblue rather than a topic about depression.
It's important to remember that Facebook is a public space. While you have control over what content you share with your friends on your own wall, whenever you post on the public page of a business or any other organisation, that content can be seen by anyone who uses Facebook.
It's a bit like ringing talkback radio or asking a question in the audience at a TV chat show - it's being broadcast everywhere, and never know who might be watching or listening.
Just as your friends can see what TV shows or movies you've liked on Facebook, they can also see your other activity.
Sorry to hear you've had this experience. I hope you understand that as Facebook is an external website, we have no control over how the platform operates and shows content to its users. As with anything on the internet, the responsibility of ensuring privacy around what information is shared lies with the user.
We do explain on our Facebook page that it is not a counselling service, helpline or crisis service. For that, we have a 24-hour support service on 1300 22 4636.
If you're wanting to talk anonymously, then we'd recommend you come to the forums here - that's why this space has been set up.
Hope this clears things up.