breaking out taxes in order_conf.html / order_conf.txt (Cart.php behaviour different than PaymentModule.php)

[codegrunt]

I have a situation where due to the Prestashop configuration, the main cart process is showing difference prices than the order receipt due to the products having taxes included on the receipt but not on the cart. What I want to have happen is that the receipt matches the cart (i.e. taxes are shown as a separate line). Customers have already been freaking out when they see that the prices appear higher on the receipt (though the total is correct).

Looking at "classes/PaymentModule.php", I see that there is a duplication of logic here that makes trying to replicate the $products list behaviour from Cart.php non-obvious. So my main question is, is there a shorthand method of calling the cart calcuation approach of Cart.php and using that in PaymentModule.php so both the receipt and cart have the same totals?

Failing that, is there a way to override at the theme level where the receipt is generated or will this definitely require changing core files (thus breaking upgrades)?

Final bonus points, anyone know if the receipt process is better integrated in upcoming versions of Prestashop? The current situatioun with PDF and email receipts is far from ideal due to the duplication of cart calculation logic (which should be centralized to one spot).

Any help appreciated.

Cheers