// app/AppKernel.php
public function registerBundles()
{
  $bundles = array(
    // [...]
    new Flosch\Bundle\StripeBundle\FloschStripeBundle()
  );
}

$stripeClient = $this->get('flosch.stripe.client');

<?php // src/YourNamespace/YourProject/Stripe/StripeClient.php

namespace YourNamespace\YourProject\Stripe;

use Flosch\Bundle\StripeBundle\Stripe\StripeClient as BaseStripeClient;

class StripeClient extends BaseStripeClient
{
    public function __construct($stripeApiKey = '')
    {
        parent::__construct($stripeApiKey);

        return $this;
    }

    public function myOwnMethod()
    {
        // Do what you want here...
    }
}

public function indexAction()
{
    // Retrieve it from the container with the old-school getter
    $stripeClient = $this->get('my.stripe.client');
}

public function indexAction(\YourNamespace\YourProject\Stripe\StripeClient $stripeClient)
{
    // Or inject it in your controllers if you use autowiring
    // Then you're ready to go...
}

/**
 * $planId (string)         : The existing Coupon ID (the one you define in the Stripe dashboard)
 */
$coupon = $stripeClient->retrieveCoupon($planId);

/**
 * $planId (string)         : The existing Plan ID (the one you define in the Stripe dashboard)
 */
$plan = $stripeClient->retrievePlan($planId);

/**
 * $customerId (string)         : The existing Customer ID
 */
$customer = $stripeClient->retrieveCustomer($customerId);

/**
 * $chargeId (string)         : The existing Charge ID
 */
$charge = $stripeClient->retrieveCharge($chargeId);

/**
 * $paymentToken (string)   : The payment token obtained using the Stripe.js library
 * $customerEmail (string)  : The customer e-mail address
 */
$stripeClient->createCustomer($paymentToken, $customerEmail);

/**
 * $planId (string)         : The existing Plan ID (the one you define in the Stripe dashboard)
 * $paymentToken (string)   : The payment token obtained using the Stripe.js library
 * $customerEmail (string)  : The customer e-mail address
 * $couponId (string|null)  : An optional coupon ID
 */
$stripeClient->subscribeCustomerToPlan($planId, $paymentToken, $customerEmail, $couponId);

/**
 * $customerId (string)     : The existing Customer ID
 * $planId (string)         : The existing Plan ID (the one you define in the Stripe dashboard)
 * $parameters (array)      : An optional array of additional parameters
 */
$stripeClient->subscribeExistingCustomerToPlan($customerId, $planId, [
    'coupon'        => 'TEST',
    'tax_percent'   => 19.6
]);

/**
 * $chargeAmount (int)              : The charge amount in cents, for instance 1000 for 10.00 (of the currency)
 * $chargeCurrency (string)         : The charge currency (for instance, "eur")
 * $paymentToken (string)           : The payment token obtained using the Stripe.js library
 * $stripeAccountId (string|null)   : (optional) The connected string account ID, default null (--> charge to the platform)
 * $applicationFee (int)            : The amount of the application fee (in cents), default to 0
 * $chargeDescription (string)      : (optional) The charge description for the customer
 */
$stripeClient->createCharge($chargeAmount, $chargeCurrency, $paymentToken, $stripeAccountId, $applicationFee, $chargeDescription);

/**
 * $chargeId (string)           : The Stripe charge ID (returned by Stripe when you create a charge)
 * $refundAmount (int)          : The charge amount in cents (if null, the whole charge amount will be refunded)
 * $metadata (array)            : additional informations about the refund, default []
 * $reason (string)             : The reason of the refund, either "requested_by_customer", "duplicate" or "fraudulent"
 * $refundApplicationFee (bool) : Wether the application_fee should be refunded aswell, default true
 * $reverseTransfer (bool)      : Wether the transfer should be reversed (when using Stripe Connect "destination" parameter on charge creation), default false
 * $stripeAccountId (string)    : (optional) TheStripe account on which the charge has been made (Stripe Connect), default null (--> refund by the platform)
 */
$stripeClient->refundCharge($chargeId, $refundAmount, $metadata, $reason, $refundApplicationFee, $reverseTransfer, $stripeAccountId);