avoid sending data when refreshed page

[eluser]ranjitbd[/eluser]
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');
$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();
}
//maybe it can be solved by using headers function to reload the page....but i dnt knw how to use it?
// thanks in advance for the solution.