Hi I appreciate your issue – here is a temporary fix, let me know if it works for you and I will get it added.
Rem out lines 591 and 616 ds-sagepay-direct.php first – then add the code below at 591
$dummy_postcode = '12345';
$countries = new WC_Countries();
$address_formats = $countries->get_address_formats();
$country_address_format = $address_formats[$this->order->billing_country];
if( strpos( $country_address_format, '{postcode}' ) )
$hidden_postcode = false;
else
$hidden_postcode = true;
$this->add_param('BillingPostCode', $hidden_postcode ? $dummy_postcode : $this->order->billing_postcode );
then add the following to where you remmed out the line that was at 616
$this->add_param('DeliveryPostCode', $hidden_postcode ? $dummy_postcode : $this->order->shipping_postcode );
Apologies if I haven’t explained it very well – if you would like I can send the modified file – let me know an email address.