Work permit for teachers

I don't know about the AU consulate but the US consulate will not notarize the letter itself but wil notarize an attached statement by you that a document is a true copy of the original.  The VN government will accept this in the case of diplomas.  If your consulate will do the same for your letter, it may work.  One big hangup may be that the school is no longer in business.  The other is that the officials can say something like "How can you have evidence that you were working when you had no work permit."  It's a regular Catch 22 situation.

If you can get them to accept such a notarized letter, please let people know.  There are several persons reading this forum who are in the same boat.  Good luck.