I have "calculated postage" on my listings. Sold an item, and the buyer paid $12.20, which according to the latest book from the Post Office, is now the rate for a 1 Kg package to anywhere in Australia. When going to print the label the price is coming up at $13.95. It has always been spot on and correct in the past, with a small discount to me for printing my own label.

 Any advice please, who should I be complaining to about this?