it should have been entered as whatever the postage method allowed. Presumably in this case Little Collins Street. That is the beauty of the system - it won't allow you to send to an invalid address, and once you find the valid address, it is, by definition, correct.

Just work with what the postage sytem allows. There is no need to complicate things. You are, after all, dealing with a bureaucracy. But the best bet is KISS and using AP addresses for AP items accords with that.