OK. I used Dreamweaver to figure out the error.

Line needed to be:

substr($order->info['shipping_method'], 0, 30));
Was missing bracket.

Code that lets me load the page is now:

Code:
if (isset($order->delivery['street_address']) && $order->delivery['street_address'] != '') {
      $shipping_data = array(
//                         'deliveryEstimate' => $order->delivery['shipping_method'],
                         'shipName' => $order->delivery['firstname'] . ' ' . $order->delivery['lastname'],
                         'shipAddress1' => $order->delivery['street_address'],
                         'shipAddress2' => $order->delivery['suburb'],
                         'shipCity' => $order->delivery['city'],
                         'shipProvince' => $province_code_ship,
                         'shipPostalCode' => $order->delivery['postcode'],
                         'shipCountry' => $order->delivery['country']['iso_code_2'],
                         'shippingMethod' => substr($order->info['shipping_method'], 0, 30));
    } else {
      $shipping_data = array();
    }
    $extra_data = array(
                         'shippingMethod' => substr($order->info['shipping_method'], 0, 30),
                         'trnComments' => 'Website Order', // $order->info['comments'],
                         // Additional Merchant-defined variables go here
                         'ref1' => $_SESSION['customer_id'],
                         'ref2' => $order_time,
                         'ref3' => zen_get_ip_address(),
                         'ref4' => $sessID,
                         'customerIp' => zen_get_ip_address()
                          );

Will update after testing this evening.

Thanks folks!