The problem solved after add it in child theme in functions.php:
// Add UTF-8 charset meta tag
function add_utf8_meta_tag() {
echo ‘<meta charset=”UTF-8″>’ . PHP_EOL;
}
add_action(‘wp_head’, ‘add_utf8_meta_tag’);

I leave it here for any other have the same problem.
No need to tell that I am very disapontiment regarding your support. This function not need to be something extra is something that your theme must have and even if you do not have the time and the resources to fix it you have to direct your clients in order to fix the problem.

Do you have estimate time of complation because is for working site and my client need it or at least give him a time frame.

Ok also all the Email notifications after i change the fort to greek language show below
????? ??????? ???? ?????????!

???? ??? %name%,

??? ???????????? ??? ??? ??????? ??? ???? %blogname%! ??? ?? ?????????????? ??? ?????????? ???, ???????????? ??? ???????? ????????:

%verification_link%