Magento – PDF Invoice; changing shipping and other text

I don't know how you add COD Charges in the order so I will write a code how to add COD Charges only in PDF Invoice in Magento core files. I highly recommend to transfer this code in the custom module that you are using.

in app/code/core/Mage/Sales/etc/config.xml -> in pdf/totals node add this:

        <codcharges translate="title">
            <title>COD Charges</title>
            <model>sales/order_pdf_total_codcharges</model>
            <font_size>7</font_size>
            <display_zero>0</display_zero>
            <sort_order>300</sort_order>
        </codcharges>

then create new file app/code/core/Mage/Sales/Model/Order/Pdf/Total/Codcharges.php with this content:

<?php
class Mage_Sales_Model_Order_Pdf_Total_Codcharges extends Mage_Sales_Model_Order_Pdf_Total_Default
{
    public function getTotalsForDisplay()
    {
        $price = 15; //or write a code to get it from where you store it for each order
        $amount = $this->getOrder()->formatPriceTxt($price);
        $label = Mage::helper('sales')->__($this->getTitle());
        $fontSize = $this->getFontSize() ? $this->getFontSize() : 7;
        $total = array(
            'amount'    => $amount,
            'label'     => $label,
            'font_size' => $fontSize
        );
        return array($total);
    }
}

For hints you can see app/code/core/Mage/Sales/Model/Order/Pdf/Total/Default.php.

To add it to the Grand Total of the Invoice please try with this:

in config.xml in sales/order_invoice/totals node add:

            <codcharges>
                <class>sales/order_invoice_total_codcharges</class>
                <after>subtotal,discount</after>
                <before>grand_total,tax</before>
            </codcharges>

Create new file app/code/core/Mage/Sales/Model/Order/Invoice/Total/Codcharges.php:

<?php
class Mage_Sales_Model_Order_Invoice_Total_Codcharges extends Mage_Sales_Model_Order_Invoice_Total_Abstract
{
    public function collect(Mage_Sales_Model_Order_Invoice $invoice)
    {
        $amount = 15; //or write a code to get it from where you store it for each order
        $invoice->setGrandTotal($invoice->getGrandTotal() + $amount);
        $invoice->setBaseGrandTotal($invoice->getBaseGrandTotal() + $amount);

        return $this;
    }
}

You can customise the sort order of totals for PDFs in XML. You will need to setup a basic module (and ensure it has dependencies of Mage_Sales and Mage_Tax), then add the following code the config.xml of your module:

Note: I have left the default ordering as is below, you can customise to your needs.

<global>
    <pdf>
        <subtotal>
            <sort_order>100</sort_order>
        </subtotal>
        <discount>
            <sort_order>200</sort_order>
        </discount>
        <tax>
            <sort_order>300</sort_order>
        </tax>
        <shipping>
            <sort_order>400</sort_order>
        </shipping>
        <adjustment_positive>
            <sort_order>500</sort_order>
        </adjustment_positive>
        <adjustment_negative>
            <sort_order>600</sort_order>
        </adjustment_negative>
        <grand_total>
            <sort_order>700</sort_order>
        </grand_total>
    </pdf>
</global>