private function getSoapClient($service, $method, array $parameters)
    {
        $timestamp = time();
        $nonce = uniqid(null, true);

        $soapClient = $this->client->buildSoapClient($service);
        $soapClient->setTimestamp($timestamp);
        $soapClient->setNonce($nonce);
        $soapClient->setSignature(array_merge($parameters, ['__method' => $method]), $this->client->getPrivateKey(), $service, $this->client->getEndpoint(), $timestamp, $nonce);

        return $soapClient;
    }