Charged an obscene postage fee for a box of air

I wished to purchase items overseas & chose to use Shopmate, associated with Australia Post thinking that my items were the safest with them. Shopmate has a calculator on their website were you can calculate approximately how much your shipping would be. I used the calculator as I had the weight and dimensions of each of the items I was purchasing and I calculated the worst case scenario price. I proceeded to purchase my items & gave the US address provided by Shopmate. Unfortunately my order had been split into three boxes as each came from a different location with the same company. Shopmate advised me of the shipping costs and I was horrified. The shipping costs was 3 times the value of my order. I instantly recognized that each box probably contained lots of packing and I immediately contacted Shopmate to have them repack my box- a facility they offered. After one month of telephoning Australia Post, i finally received a response that they couldn't be repacked. I paid the excessive postage and received lightest boxes which were 3/4 empty! Each box was packed with air pillows which could have been removed because the items came in their own packaging! Shame on you Australia Post