Trying to use on a GBP site

Hello there,
This is an issue that is to be fixed in the next iteration of the plugin. However, I am a few weeks away from my next sprint.

In the meantime though here are 2 changes you can make to workaround the issue:
1) On line 185 of woocommerce-globalpay.php change:
'currency' => 'NGN',
to
'currency' => $order->get_order_currency(),

2) On line 78 of woocommerce-globalpay.php insert a new line so that

function is_valid_for_use() {
 if (!in_array(get_option('woocommerce_currency'), array('NGN'))) {

becomes

function is_valid_for_use() {
return TRUE;
 if (!in_array(get_option('woocommerce_currency'), array('NGN'))) {

These changes should workaround the issue for now. When the next version is released it will incorporate these changes

Good luck.