ÅÄÖ (swedish characters) problems on update - php

Question

I have some problems with displaying ÅÄÖ in jcart, I'm not very good at explaining but if you look here you'll see what I mean.
At first it all seems to work, but if you update the page or go to the checkout it doesn't. If you press "Ta bort" or add another item after updating the characters will be displayed correctly again. I use UTF-8 as charset and I've tried ISO-8859-1 which use to fix these problems, but instead it shows another symbol. Don't know exactly where the problem is so please tell me, if you have a clue, what you need more information about.
Looking at the demo may give you some ideas? Thanks!
To show the cart I have this: <?php $jcart->display_cart();?>
And here's some code from jcart.php (included file):
/**
* Process and display cart
*/
public function display_cart() {
$config = $this->config;
$errorMessage = null;
// Simplify some config variables
$checkout = $config['checkoutPath'];
$priceFormat = $config['priceFormat'];
$id = $config['item']['id'];
$name = $config['item']['name'];
$price = $config['item']['price'];
$qty = $config['item']['qty'];
$url = $config['item']['url'];
$add = $config['item']['add'];
// Use config values as literal indices for incoming POST values
// Values are the HTML name attributes set in config.json
$id = $_POST[$id];
$name = $_POST[$name];
$price = $_POST[$price];
$qty = $_POST[$qty];
$url = $_POST[$url];
// Optional CSRF protection, see: http://conceptlogic.com/jcart/security.php
$jcartToken = $_POST['jcartToken'];
// Only generate unique token once per session
if(!$_SESSION['jcartToken']){
$_SESSION['jcartToken'] = md5(session_id() . time() . $_SERVER['HTTP_USER_AGENT']);
}
// If enabled, check submitted token against session token for POST requests
if ($config['csrfToken'] === 'true' && $_POST && $jcartToken != $_SESSION['jcartToken']) {
$errorMessage = 'Invalid token!' . $jcartToken . ' / ' . $_SESSION['jcartToken'];
}
// Sanitize values for output in the browser
$id = filter_var($id, FILTER_SANITIZE_SPECIAL_CHARS, FILTER_FLAG_STRIP_LOW);
$name = filter_var($name, FILTER_SANITIZE_SPECIAL_CHARS, FILTER_FLAG_STRIP_LOW);
$url = filter_var($url, FILTER_SANITIZE_URL);
// Round the quantity if necessary
if($config['decimalPlaces'] === true) {
$qty = round($qty, $config['decimalPlaces']);
}
// Add an item
if ($_POST[$add]) {
$itemAdded = $this->add_item($id, $name, $price, $qty, $url);
// If not true the add item function returns the error type
if ($itemAdded !== true) {
$errorType = $itemAdded;
switch($errorType) {
case 'qty':
$errorMessage = $config['text']['quantityError'];
break;
case 'price':
$errorMessage = $config['text']['priceError'];
break;
}
}
}
// Update a single item
if ($_POST['jcartUpdate']) {
$itemUpdated = $this->update_item($_POST['itemId'], $_POST['itemQty']);
if ($itemUpdated !== true) {
$errorMessage = $config['text']['quantityError'];
}
}
// Update all items in the cart
if($_POST['jcartUpdateCart'] || $_POST['jcartCheckout']) {
$cartUpdated = $this->update_cart();
if ($cartUpdated !== true) {
$errorMessage = $config['text']['quantityError'];
}
}
// Remove an item
/* After an item is removed, its id stays set in the query string,
preventing the same item from being added back to the cart in
subsequent POST requests. As result, it's not enough to check for
GET before deleting the item, must also check that this isn't a POST
request. */
if($_GET['jcartRemove'] && !$_POST) {
$this->remove_item($_GET['jcartRemove']);
}
// Empty the cart
if($_POST['jcartEmpty']) {
$this->empty_cart();
}
// Determine which text to use for the number of items in the cart
$itemsText = $config['text']['multipleItems'];
if ($this->itemCount == 1) {
$itemsText = $config['text']['singleItem'];
}
// Determine if this is the checkout page
/* First we check the request uri against the config checkout (set when
the visitor first clicks checkout), then check for the hidden input
sent with Ajax request (set when visitor has javascript enabled and
updates an item quantity). */
$isCheckout = strpos(request_uri(), $checkout);
if ($isCheckout !== false || $_REQUEST['jcartIsCheckout'] == 'true') {
$isCheckout = true;
}
else {
$isCheckout = false;
}
// Overwrite the form action to post to gateway.php instead of posting back to checkout page
if ($isCheckout === true) {
// Sanititze config path
$path = filter_var($config['jcartPath'], FILTER_SANITIZE_URL);
// Trim trailing slash if necessary
$path = rtrim($path, '/');
$checkout = $path . '/gateway.php';
}
// Default input type
// Overridden if using button images in config.php
$inputType = 'submit';
// If this error is true the visitor updated the cart from the checkout page using an invalid price format
// Passed as a session var since the checkout page uses a header redirect
// If passed via GET the query string stays set even after subsequent POST requests
if ($_SESSION['quantityError'] === true) {
$errorMessage = $config['text']['quantityError'];
unset($_SESSION['quantityError']);
}
////////////////////////////////////////////////////////////////////////
// Output the cart
// Return specified number of tabs to improve readability of HTML output
function tab($n) {
$tabs = null;
while ($n > 0) {
$tabs .= "\t";
--$n;
}
return $tabs;
}
// If there's an error message wrap it in some HTML
if ($errorMessage) {
$errorMessage = "<p id='jcart-error'>$errorMessage</p>";
}
// Display the cart header
echo tab(1) . "$errorMessage\n";
echo tab(1) . "<form method='post' action='$checkout'>\n";
echo tab(2) . "<fieldset>\n";
echo tab(3) . "<input type='hidden' name='jcartToken' value='{$_SESSION['jcartToken']}' />\n";
echo tab(3) . "<table border='0'>\n";
echo tab(4) . "<thead>\n";
echo tab(5) . "<tr>\n";
echo tab(6) . "<th colspan='3'>\n";
echo tab(7) . "<div align='center'><span style='font-size:24px;' id='jcart-title'><br />VARUKORG</span> ($this->itemCount $itemsText) </div>\n";
echo tab(6) . "</th>\n";
echo tab(5) . "</tr>". "\n";
echo tab(4) . "</thead>\n";
// Display the cart footer
echo tab(4) . "<tfoot>\n";
echo tab(5) . "<tr>\n";
echo tab(6) . "<th colspan='3'>\n";
// If this is the checkout hide the cart checkout button
if ($isCheckout !== true) {
if ($config['button']['checkout']) {
$inputType = "image";
$src = " src='jcart/images/checkout.gif' alt='{$config['text']['checkout']}' title='' ";
}
echo tab(7) . "<input type='$inputType' $src id='jcart-checkout' name='jcartCheckout' class='jcart-button' value='{$config['text']['checkout']}' /> \n";
}
echo tab(7) . "<span id='jcart-subtotal'>{$config['text']['subtotal']}: <strong>" . number_format($this->subtotal, $priceFormat['decimals'], $priceFormat['dec_point'], $priceFormat['thousands_sep']) . " </strong></span>\n";
echo tab(6) . "</th>\n";
echo tab(5) . "</tr>\n";
echo tab(4) . "</tfoot>\n";
echo tab(4) . "<tbody>\n";
// If any items in the cart
if($this->itemCount > 0) {
// Display line items
foreach($this->get_contents() as $item) {
echo tab(5) . "<tr>\n";
echo tab(6) . "<td class='jcart-item-qty'>\n";
echo tab(7) . "<input name='jcartItemId[]' type='hidden' value='{$item['id']}' />\n";
echo tab(7) . "<input id='jcartItemQty-{$item['id']}' name='jcartItemQty[]' size='1' style='margin:0;padding:0;width:20px;' type='text' value='{$item['qty']}' />\n";
echo tab(6) . "</td>\n";
echo tab(6) . "<td class='jcart-item-name'>\n";
if ($item['url']) {
echo tab(7) . "<a href='{$item['url']}'>{$item['name']}</a>\n";
}
else {
echo tab(7) . $item['name'] . "\n";
}
echo tab(7) . "<input name='jcartItemName[]' type='hidden' value='{$item['name']}' />\n";
echo tab(6) . "</td>\n";
echo tab(6) . "<td class='jcart-item-price'>\n";
echo tab(7) . "<span>" . number_format($item['subtotal'], $priceFormat['decimals'], $priceFormat['dec_point'], $priceFormat['thousands_sep']) . "</span><input name='jcartItemPrice[]' type='hidden' value='{$item['price']}' />\n";
echo tab(7) . "<a class='jcart-remove' href='?jcartRemove={$item['id']}'>{$config['text']['removeLink']}</a>\n";
echo tab(6) . "</td>\n";
echo tab(5) . "</tr>\n";
}
}