/**
  * Sends the CancelPendingShipmentRequest and returns the response
  *
  * @param ComplexType\CancelPendingShipmentRequest $cancelPendingShipmentRequest 
  * @return stdClass
  */
 public function getCancelPendingShipmentReply(ComplexType\CancelPendingShipmentRequest $cancelPendingShipmentRequest)
 {
     return $this->_soapClient->cancelPendingShipment($cancelPendingShipmentRequest->toArray());
 }
<?php

require_once 'credentials.php';
require_once 'bootstrap.php';
use FedEx\ShipService, FedEx\ShipService\ComplexType, FedEx\ShipService\SimpleType;
$userCredential = new ComplexType\WebAuthenticationCredential();
$userCredential->setKey(FEDEX_KEY)->setPassword(FEDEX_PASSWORD);
$webAuthenticationDetail = new ComplexType\WebAuthenticationDetail();
$webAuthenticationDetail->setUserCredential($userCredential);
$clientDetail = new ComplexType\ClientDetail();
$clientDetail->setAccountNumber(FEDEX_ACCOUNT_NUMBER)->setMeterNumber(FEDEX_METER_NUMBER);
$version = new ComplexType\VersionId();
$version->setServiceId('ship')->setMajor(10)->setIntermediate(0)->setMinor(0);
$trackingId = new ComplexType\TrackingId();
$trackingId->setTrackingNumber('12345')->setTrackingIdType(SimpleType\TrackingIdType::_FEDEX);
$cancelPendingShipmentRequest = new ComplexType\CancelPendingShipmentRequest();
$cancelPendingShipmentRequest->setWebAuthenticationDetail($webAuthenticationDetail);
$cancelPendingShipmentRequest->setClientDetail($clientDetail);
$cancelPendingShipmentRequest->setVersion($version);
$cancelPendingShipmentRequest->setTrackingId($trackingId);
var_dump($cancelPendingShipmentRequest->toArray());
$validateShipmentRequest = new ShipService\Request();
$validateShipmentRequest->getSoapClient()->__setLocation('https://ws.fedex.com:443/web-services/ship');
$response = $validateShipmentRequest->getCancelPendingShipmentReply($cancelPendingShipmentRequest);
var_dump($response);