public function login($credentials)
{
$user = $credentials['user'];
$password = $credentials['apipassword'];
$wsdlUrl = 'http://ws.tradetracker.com/soap/affiliate?wsdl';
//Setting the client.
$this->_apiClient = new \SoapClient($wsdlUrl, array('encoding' => 'UTF-8', 'compression' => SOAP_COMPRESSION_ACCEPT | SOAP_COMPRESSION_GZIP | SOAP_COMPRESSION_DEFLATE, 'soap_version' => SOAP_1_1));
$this->_apiClient->authenticate($user, $password, false, 'en_GB');
}