Array
(
	[api_password] => xapitest
	[api_login] => xapitest
	[method] => playerExists
	[user_username] => domendomen2
	[currency] => EUR
)

OK:
{  
   "error":0,
   "response":{  
      "id":41457, //remote_id that will be sent in seamless request
      "username":"xxdomendomen2",
      "balance":"20.00",
      "currencycode":"EUR",
      "created":"2013-02-15 14:57:47",
      "agent_balance":"0.25"
   }
}

DOESN'T EXIST:
{"error":0,"response":false}

public function playerExists(){    //returns FALSE on no user, else returns details
	return $this->client->checkPlayer($this->user['username']);
}