Try this and see if it works ...
Edit the module:
/includes/modules/order_total/ot_shipping.php
and replace the function process with:
function process() {
global $order, $currencies;
if ($order->info['shipping_cost'] == 0) {
// do not show it
} else {
// show it
$this->output[] = array('title' => $order->info['shipping_method'] . ':',
'text' => $currencies->format($order->info['shipping_cost'], true, $order->info['currency'], $order->info['currency_value']),
'value' => $order->info['shipping_cost']);
}
}
This will make it not show in the checkout ... then change the language file for:
/includes/languages/english/modules/order_total/ot_shipping.php
Line #25 : define('FREE_SHIPPING_TITLE', 'Free Shipping');
to read how you want it to appear in the My Account ...
I am guessing that this should work with your add on as well ...