For instance... instead of:
<?php echo WA_PP_ECO_GetValue($WA_PP_ECO_GetResult, "LastName"); ?>
It should be:
<?php echo $_SESSION["eCartCheckoutForm_lastname"]; ?>
<?php echo((isset($_POST["tax"]))?$_POST["tax"]:"") ?>
it should be:
<?php echo WA_eCart_DisplayMoney($CESmith, $CESmith->GetTax()); ?>
You can't refer to $_POST or WA_PP_ECO_GetValue on the success page. You need to refer to the cart or session directly.