public function updateDefaultCard($cardId)
    {
        // first lets update the default source for the stripe customer
        $customer = $this->asStripeCustomer();
        $customer->default_source = $cardId;
        $result = $customer->save();

        // now lets update the users default card
        $card = $this->getCard($cardId);

        $this->card_brand = $card->brand;
        $this->card_last_four = $card->last4;

        $this->save();

        return $this;
    }