Firstly, my reply to negative feedback would be as concise and as professional as possible - stating the facts like postage costs etc.

I will now address couple of points made by some of the other members. It is not difficult to log in and use Australia Post calculator. There is no such thing as $2.80 postage for books, unless they are passed on as letters / documents. The thickness of those parcels can not exceed 20mm and this is very quickly picked up by postal stuff when paying to have the item sent.

So to cut to the chase minimum charges for books are $6.50 + bag / satchel = $7.50. If the item is registered it costs an additional $3.50.

The postal charges are the same, whether the parcel is posted within the same city that you reside in, or across Australia.

Communication with buyers / sellers is very important and I would myself make contact the buyer and state the facts. If the postage cost less somehow I would myself refund the money / difference. between your cost and the cost charged.

I hope this helps.