Fixed Delivery Charge Problem

I've created a powerstore site for an Australian client and cannot set it up with your American shipping providers. Instead I have set up fixed rates using eCart (which I also purchased because I needed powerstore to be functional outside of the US).

I created a drop down list on the cart page, and the calculation is done in eCart Charges based on a session variable.

So far, so good. The selection of the delivery location adds the correct amount to the cart total in the charges area. The customer clicks on checkout button, then the paypal button is pressed and paypal details are confirmed. The customer is then taken back to the powerstore site "order confirmation" page.

This is where the problem is. The order confirmation total is not the same as the cart total. The charges always default to the highest shipping amount of $20, even if they selected the "free pick up" option.

Can you please let me know how I can correct this problem?

Or, if you've got a better solution for setting up fixed delivery charges in Powerstore (using eCart) I'd happily change the rather clunky way I have it set up now!

It's a concern because at the moment my client is having to reimburse her customers the difference.

My test site is at voyagermoon
The live site is at www.voyagermoon.com.au