This is not new - last year I had two items returned to me because of a one letter spelling mistake.  Really!   You must have better customers Lol

Ive also had them send back because buyers put a second locator (like some random creek running through their property!) on their address (including their regular address), and writing suburb or state in the incorrect format, even with correct postcode, for example  -

123 la la St

blah blah

North Vic

Instead of

123 lala st

Blah blah North

Vic

Either way, you posted to the address provided by the buyer - their fault it was returned to you.

I gave my buyers the option to pay for postage AGAIN and supply correct address, or cancel the item and get a refund, not including postage costs. From memory they usually pay postage again rather than cancel.