After you create the configuration
you are need instance a few next services.
Signer provider is the services what provide Signer for each gateway.
use Pixidos\GPWebPay\Signer\SignerFactory;
use Pixidos\GPWebPay\Signer\SignerProvider;
$signerProvider = new SignerProvider(new SignerFactory(), $config->getSignerConfigProvider());
Request factory is helper what provide creating Request object from request.operation
use Pixidos\GPWebPay\Factory\RequestFactory;
$requestFactory = new RequestFactory($config->getPaymentConfigProvider(), $signerProvider);
Service for creating Response from received params
use Pixidos\GPWebPay\Factory\ResponseFactory;
$responseFactory = new ResponseFactory($config->getPaymentConfigProvider());
Is service what validate and can processed Response
use Pixidos\GPWebPay\ResponseProvider;
$provider = new ResponseProvider(
$config->getPaymentConfigProvider(), $signerProvider
);