Hi,
Thanks !
Can you please replace the line
'<description>'.$product->order_product_name.'</description>'.
By
'<description>'.strip_tags($product->order_product_name).'</description>'.
It should fix the issue.
It you have still problems with the "SagePay basket XML" ; you can replace the line
$postData['BasketXML'] = $bxml;
By
// $postData['BasketXML'] = $bxml;
To avoid the addition of the basket in the content.
I added an option for the next build, so it will be possible to activate or deactivate the basket.
We will processed some new tests, I guess that some tests where missing with the variants
Regards,