System.ServiceProcess.TimeoutException: Time out has expired and the operation has not been completed.

ServiceController service = new ServiceController("ModbusAgent");
service.Stop();
TimeSpan timeout = new TimeSpan(50000);
service.WaitForStatus(ServiceControllerStatus.Stopped, timeout); 

ServiceController service = new ServiceController("ModbusAgent");
service.Stop();
service.WaitForStatus(ServiceControllerStatus.Stopped);