Expired session & csrf_protection

[eluser]ci_user[/eluser]
[quote author="CroNiX" date="1338495649"]The way they coded it, the only way is to extend the CI_Security class and override the csrf_show_error() method with your own.[/quote]

Ok, I'm trying that but how can I redirect in the csrf_show_error method?

Code:

public function csrf_show_error()
    {
        // show_error('The action you have requested is not allowed.');
  redirect('myController');
     }

Gives me the error "Call to undefined function redirect()".

Code:

public function csrf_show_error()
    {
        // show_error('The action you have requested is not allowed.');
   $this->load->helper('url');
   redirect('benefits');
     }

Gives me the error "Call to a member function helper() on a non-object".

Am I missing something?