how call another php file to Codeigniter view

how call .php outside the folder

my folder structurer is

I'm in cart.php

my code is

$tpl_file ='../mail.php';//problem is here LINE 279
$msg_tmpl = file_get_contents($tpl_file);
if (!file_exists($tpl_file))
   {
?>
   <script>
     alert('no');
   </script>
<?php
   }
   else
   {
   ?>
      <script>
         alert('yes');
      </script>
   <?php
 }

So my question is I want to get all data from the mail.php and assign it $tpl_file.

In above try I'm getting always NO with

A PHP Error was encountered

Severity: Warning

Message: file_get_contents(../mail.php): failed to open stream: No such file or directory

Filename: pages/cart.php

Line Number: 279

any Ideas??