Fix method call

export.php

@@ -56,7 +56,7 @@ if ($mform->is_cancelled()) {
     redirect($returnurl);
 } elseif ($formdata) {
     $exporter = new exporter($formdata);
-    $exporter->csv_download();
+    $exporter->send_file();
 } else {
     $mform->set_data($formdata);
 }