Binding type string in a specific column with phpspreadsheet

Question

this phpspreadsheet is really good but really documentationless. So, I read a lot and was trying to define my personal valueBinder, and I think that is correct but is not executed i suppose.

First thing first i create my binder like this :

class MyValueBinder extends DefaultValueBinder{
/**
 * Bind value to a cell.
 *
 * @param Cell $cell Cell to bind value to
 * @param mixed $value Value to bind in cell
 *
 * @return bool
 */
   public function bindValue(Cell $cell, $value){
       if($cell->getColumn() == 'D'){
          // Set value explicit
          //$cell->setValueExplicit($value, DataType::TYPE_STRING);
          $cell->setValueExplicit("ok", DataType::TYPE_STRING);
       }
       return parent::bindValue($cell, $value);
   }
}

Like you can see i was simply binding the type string for every cell in D column, then I tried to put the value ok in every cell in D column just for debug.

Then in my main page:

require 'vendor/autoload.php';

use PhpOffice\PhpSpreadsheet\Cell\Cell;

\PhpOffice\PhpSpreadsheet\Cell\Cell::setValueBinder(new \PhpOffice\PhpSpreadsheet\Cell\MyValueBinder());

$reader = new \PhpOffice\PhpSpreadsheet\Reader\Xls();

//After this I load my file e do some modifications and then I make
// a Writer CSV and write everything on a csv file.

At this point came the sadness because in the csv file i find the same wrong value, just for example if I have a number like 1345 in the csv I have 1,345

I don't want to rescan the CSV to correct this thing also because i have tens of thousands of rows