// Connect to Australia Post to retrieve a live shipping quote
$validQuote = false;
$ausPostURL = 'http://drc.edeliver.com.au/ratecalc.asp?';
$postVars = array(
    'Height' => $height,
    'Length' => $length,
    'Width' => $width,
    'Weight' => $weight,
    'Quantity' => 1,
    'Pickup_Postcode' => $this->_origin_zip,
    'Destination_Postcode' => $this->_destzip,
    'Country' => $this->_destcountry,
    'Service_Type' => $this->_deliverytype
);

$postRequest = '';
foreach($postVars as $k => $v) {
    $postRequest .= '&'.$k.'='.urlencode($v);
}
$postRequest = ltrim($postRequest, '&');

$result = PostToRemoteFileAndGetResponse($ausPostURL, $postRequest);