Jquery Ajax does not update values in mysql

Hello i am trying to update data taken from modal form with ajax. I submit the data correctly but for some reason they do not get updated in database.

My Javascript code:

<script>
    jQuery(document).ready(function ($) {
        var modalId = '<?php echo $row['csid']?>';

        var feedback = null;
        var homepage_teaser = null;
        var review_comment = null;
        var review_visible_website = null;
        var dataString = null;

        var review_rating = '<?php echo $row['rating']?>';
        var booking_csid = '<?php echo $row['csid']?>';
        var property_id = '<?php echo $row['currentPropertyId']?>';
        var review_customer_id = '<?php echo $row['cusid']?>';

        $("#saveButton_"+modalId).click(function () {

            feedback = $('#feedback_'+ modalId).val();
            homepage_teaser = $('#teaser_'+ modalId).val();
            review_comment = $('#feedbackcomment_'+ modalId).val();
            review_visible_website = $('#checkbox_'+ modalId).val();

            dataString = 'feedback='+ feedback + '&homepage_teaser='+ homepage_teaser + '&review_comment=' + review_comment + '&review_visible_website=' + review_visible_website+ '&review_rating=' + review_rating+ '&booking_csid=' + booking_csid+ '&property_id=' + property_id + '&review_customer_id=' + review_customer_id;
            $.ajax({
                type: "POST",
                url: "ajax/feedback_overview_update.php",
                data: dataString,
                cached: false,
                success: function () {
                    alert("Updated: " + dataString);
                },
                error: function () {
                    alert("failure");
                }
            });
            console.log("Modal Submited: " + modalId);
            console.log("Modal Data: " + dataString);
        });
    });
</script>

and the php script:

try{
        $handler = new PDO("mysql:host=$dbhost;dbname=$dbname", "$dbuser", "$dbpass");
        $handler->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $handler->setAttribute(PDO::MYSQL_ATTR_INIT_COMMAND, "SET NAMES utf8mb4 ");
        $handler->exec("SET CHARACTER SET UTF-8 ");
    }catch(Exception $e){
        echo $e->getMessage();
        die();
    }

    $feedback = $_GET['feedback'];
    $homepage_teaser = $_GET['homepage_teaser'];
    $review_comment = $_GET['review_comment'];
    $review_visible_website = $_GET['review_visible_website'];
    $review_rating = $_GET['review_rating'];
    $booking_csid = $_GET['booking_csid'];
    $property_id = $_GET['property_id'];
    $review_customer_id = $_GET['review_customer_id'];


    $updatefeedback = $handler->prepare("UPDATE reviews SET feedback = ?, homepage_teaser = ?, review_comment = ?, review_visible_website = ?, review_rating = ?, review_checked = 'yes', review_checked_date = NOW() WHERE booking_csid = ? AND property_id = ? AND review_customer_id = ?");

    $updatefeedback->bindValue(1, $feedback);
    $updatefeedback->bindValue(2, $homepage_teaser);
    $updatefeedback->bindValue(3, $review_comment);
    if ($review_visible_website == 'on') {
        $updatefeedback->bindValue(4, 'yes');
    } else {
        $updatefeedback->bindValue(4, 'no');
    }



    $updatefeedback->bindValue(5, $review_rating);
    $updatefeedback->bindValue(6, $booking_csid);
    $updatefeedback->bindValue(7, $property_id);
    $updatefeedback->bindValue(8, $review_customer_id);

    $updatefeedback->execute();

    if ($updatefeedback) {
        echo "Success";
    } else {
        echo "Failure";
    }

And here is the dataString value:

Modal Data: feedback=Sehr schön&homepage_teaser=this is homepage&review_comment=this is feedback comment&review_visible_website=on&review_rating=3.25&booking_csid=1679&property_id=87&review_customer_id=22

But still they are not updated. What am i doing wrong?