avoid resend data when click on refresh menu

Code:
//how to avoid sending data into database when click on refresh button.

//i already set validation.so no one can submit any empty feedback.but when a feed back //is submitted and show the session message to the

//user that feedback submitted successfully.then if i click on refresh in the browser it //submitted again.

//i can redirect to another page to avoid this.but i want to stay in the same feed back //page..



//here is my code



  function feedback()

  {   

      $data = array();

      $data[‘mainContent’] = $this->load->view(‘tmbd/feedback’, $data, true);

      $this->load->view(‘index’, $data);

  }

 

  function feedbackSave()

  {

      $data=array();

     

      $data[‘subject’] = $this->input->post(‘subject’, true);

      $data[‘name’] = $this->input->post(‘lname’, true);

      $data[‘address’] = $this->input->post(‘address’, true);

      $data[‘email’] = $this->input->post(‘email’, true);

      $data[‘mobile’] = $this->input->post(‘mobile’, true);

      $data[‘comments’] = $this->input->post(‘comments’, true);

     

      $datetime = date(‘Y-m-d H:i:s’);

      $data[‘date’] = $dateTime;



      $this->load->model($this->config->item(‘generalModel’), ‘save_feedback’,TRUE);

      $this->save_feedback->feedbackSave($data);

     

      $this->session->set_flashdata(‘feedback’, ‘Feedback send successfully’);

      $this->feedback();

  }

// i cant go to another page.i have to show that feedback page to user even after submit feed back just with a flash message.

//maybe it can be solved by using headers function to reload the page….but i dnt knw how to use it?