I can confirm that this made it work. Thank you Nicolas. No more errors and the payment went through, and also posted in FirstData.
However, it is not confirming the the transaction in hikashop. Just says created. Any ideas?
1) So after talking to FirstData they said everything is set up and it's the carts fault, which i don't believe. Could it be that my relay response return url and and receipt link url is set incorrectly at first data? Both are:
http://www.websitename.com/index.php?option=com_hikashop&ctrl=checkout&task=notify&notif_payment=authorize&tmpl=component&lang=en&Itemid=183
should it be?
http://www.websitename.com/index.php?option=com_hikashop&ctrl=checkout&task=notify¬if_payment=authorize&tmpl=component&lang=en
2) Also i left the return URL in the hikashop plugin empty.
3) Should the Receipt Link URL and the Relay Response URL match? Or is that yet another link? If so which one.
Because: x_relay_url : Invalid x_relay_url. Must be the same as configured for the payment page