urgent- error only on some users at checkout

suddenly there is a problem with only some users at checkout
500 error returned

log file attached

Did that fix from the link above but no such luck

maybe i inserted wrong

/**
* @package HikaShop for Joomla!
* @version 1.5.7
* @author hikashop.com
* @copyright (C) 2010-2012 HIKARI SOFTWARE. All rights reserved.
* @license GNU/GPLv3 www.gnu.org/licenses/gpl-3.0.html
*/
defined('_JEXEC') or die('Restricted access');
?>
<?php
if($this->identified){
?>
<div <?php
if($this->has_shipping){
echo 'id="hikashop_checkout_address" class="hikashop_checkout_address"';
}else{
echo 'id="hikashop_checkout_address_billing_only" class="hikashop_checkout_address_billing_only"';
} ?>>
<div <?php
if($this->has_shipping){
echo 'id="hikashop_checkout_address_left_part" class="hikashop_checkout_address_left_part"';
}else{
echo 'id="hikashop_checkout_billing_address" class="hikashop_checkout_billing_address"';
} ?>>
<fieldset>
<legend><?php echo JText::_('HIKASHOP_BILLING_ADDRESS');?></legend>
<?php
$this->type = 'billing';
echo $this->loadTemplate('view');
if($this->has_shipping){
?>
</fieldset>
</div>
<div id="hikashop_checkout_address_right_part" class="hikashop_checkout_address_right_part">
<fieldset>
<legend><?php echo JText::_('HIKASHOP_SHIPPING_ADDRESS');?></legend>
<?php
$checked = '';
$style = '';
$override = false;
if(!isset($this->currentShipping))$this->currentShipping = '';
if(method_exists($this->currentShipping, 'getShippingAddress')) {
$override = $this->currentShipping->getShippingAddress();
}
if($override === false) {
if($this->shipping_address==$this->billing_address){
$checked = 'checked="checked" ';
$style = ' style="display:none"';
}?>
<input class="hikashop_checkout_shipping_same_address inputbox" <?php echo $checked; ?>type="checkbox" id="same_address" name="same_address" value="yes" alt="Same address" onclick="return hikashopSameAddress(this.checked);" />
<label for="same_address"><?php echo JText::_('SAME_AS_BILLING');?></label>
<div class="hikashop_checkout_shipping_div" id="hikashop_checkout_shipping_div" <?php echo $style;?>>
<?php
$this->type = 'shipping';
echo $this->loadTemplate('view');
?>
</div>
<?php } else {
?> <span class="hikashop_checkout_billing_address_info"><?php echo $override;?></span>
<?php }
} ?>
</fieldset>
</div>
</div>
<div style="clear:both"></div>
<?php
}else{
}

Must have copied the wrong bit of code,
sorry for the brain fart, was awakened with a phone call and been at it since

that seems to have done it

will keep testing all users

thanks again for the outstanding response and support