Phpexcel - русский текст отображается некорректно

require_once('../Classes/PHPExcel.php');
 
require_once('../Classes/PHPExcel/IOFactory.php');
 
require_once('../Classes/PHPExcel/Writer/Excel5.php');
 
$order_array = array (
                1 => "A15", 2 => "D15", 3 =>"G15", 4=>"J15", 5=>"M15", 6=>"P15", 7=>"S15", 8=>"V15", 9=>"Y15", 10=>"AB15",
                11 =>"AE15", 12=>"AH15", 13=>"AK15", 14=>"AN15", 15=>"AQ15", 16=>"AT15", 17=>"AW15", 18=>"AZ15", 19=>"BC15",
                20=>"BF15", 21=>"BI15", 22=>"BL15", 23=>"BO15", 24=>"BR15", 25=>"BU15", 26=>"BX15", 27 =>"CA15", 28=>"CD15", 29=>"CG15",
                30=>"CJ15", 31=>"CM15", 32=>"CP15", 33=>"CS15", 34=>"CV15", 35=>"CY15", 36=>"DB15",37=>"DE15",38=>"DH15", 39=>"DK15",
                40=>"DN15", 41=>"DQ15", 42=>"DT15", 43=>"DW15", 44=>"DZ15", 45=>"EC15", );
 
if (
        (!empty($_POST['order'])) 
    and
        (!empty($_POST['company_type']))
    and
        (!empty($_POST['company_name']))
    and
        (!empty($_POST['info_company']))
    and
        (!empty($_POST['egrip']))
    and
        (!empty($_POST['ur_adres1']))   
    and
        (!empty($_POST['ur_adres2']))
    and
        (!empty($_POST['option_check']))
    and
        (!empty($_POST['okved']))
    and
        (!empty($_POST['company_type2']))
    )
      {
      echo 'progress<br>';
      $order = $_POST['order'];
//    $order = iconv ('Windows-1251','UTF-8',$order);
//    $order = iconv ('UTF-8','Windows-1251',$order);
      $company_type = $_POST['company_type'];
      $company_name = $_POST['company_name'];
      $info_company = $_POST['info_company'];
      $egrip = $_POST['egrip'];
      $ur_adres1 = $_POST['ur_adres1'];
      $ur_adres2 = $_POST['ur_adres2'];
      $option_check = $_POST['option_check'];
      $okved = $_POST['okved'];
      $company_type2 = $_POST['company_type2'];
      $company_type2 = iconv ('Windows-1251','UTF-8',$company_type2);
    
      }
     else
        {
        echo 'POST-ERROR' ; 
        }
//--------------------Create xls file---------------------------------------------------->    
$book = PHPExcel_IOFactory::load("testDoc.xls");
 
if (strlen($order) <=100)
    {
    for ($i = 1 ; $i <=45 ; $i++)
        {
    $book->getActiveSheet()->setCellValue($order_array[$i],$order[$i-1]);    
    $objWriter = PHPExcel_IOFactory::createWriter($book, 'Excel5');
        }
    }
else echo 'some think wrong!!!!' .strlen($order).'<br>';     
 
$objWriter->save('new_read.xls');

$order = utf8_encode($order);

echo mb_strlen($word, 'UTF-8');

<?php
    $word = "привет мир";
    echo mb_strlen($word, 'UTF-8');
?>

<?php header('Content-Type: text/html; charset=UTF-8'); ?>

$order = iconv('UTF-8', 'ISO-8859-1', $order); // у вас же исходное в UTF-8?
$order = utf8_encode($order);

$str = 'Строка';
$count = mb_strlen($str, 'UTF-8');
$arr = array();
for ($i=0; $i<$count; $i++) {
   $arr[] = mb_substr($str, $i, 1, 'UTF-8');
}
echo '<pre>';
print_r($arr);
echo '</pre>';