public function setBillingInfo($holderName, $number, $expirationMonth, $expirationYear)
    {
        $this->client->addQueryString('new_vault', true);

        $this->data->billing_info = new stdClass;

        $creditCard = $this->data->billing_info->credit_card = new stdClass;
        $creditCard->holder_name = $holderName;
        $creditCard->number = $number;
        $creditCard->expiration_month = $expirationMonth;
        $creditCard->expiration_year = $expirationYear;

        return $this;
    }