Flashes to generic thank you page

Greetings!
I have installed Hikashop Essential with added Styles on Joomla 2.5. I have put my thank-you page in the Return URL but it flashes to the generic page for a few seconds before going to my designated one.

Is this a bug perhaps? If not, can I somehow get round this so that it goes straight to my designated page without showing the generic one first?
Many thanks in advance
Chris

Sorry, I should have been clearer. Once payment is taken, the next page is this one keepsakebooks.co.uk/index.php/choose-you...checkout/step/step-3 which is the generic page. When you put this link in your browser it will look like a nicely formatted page but it does not show like that - it is unformatted as in the screenshot below.

Where I want them to go is here : keepsakebooks.co.uk/index.php/post-payment - screenshot below. I have this URL in the Return Url box.

So on completion of payment, first the generic page is shown in unformatted form as per the screenshot for a few seconds before then continuing to the post-payment url which I want. Can I avoid this blip to the generic page? Thanks - appreciate your help.

Hi,

You will probably have to edit the file xxx_thanks.php of the payment plugin you are using.
In this file just make a redirection to the desired url.

You have to make this changes via ftp.

Thanks Xavier. Sadly I do not speak 'php'....I have located the relevant bit of the xxx_thanks.php which is shown below. Please can you tell me where to add my specific url ( keepsakebooks.co.uk/index.php/post-payment ). Many thanks indeed....

<?php echo JText::_('THANK_YOU_FOR_PURCHASE');
if(!empty($return_url)){
echo '<br/><a href="'.$return_url.'">'.JText::_('GO_BACK_TO_SHOP').'</a>';
}?>

You can use the code:

<?php      
  header('Location: http://keepsakebooks.co.uk/index.php/post-payment');      
?>

THAT'S IT!! THANKYOU, THANKYOU, THANKYOU.
Chris