It seems the postback URL is blocked:
Forbidden
You don't have permission to access /?wc-api=Wc_Pay_Gateway_Exchange&action=new_ppt&pincode=271&website_location_id=1&website_id=2&program_id=xxxxxxxxxxxxxxxx
I also did receive an email from pay.nl stated the same
might be caused by modsecurity comodo rules. might be somethinge else.
Any suggestion? or solution.
Alex
https://wordpress.org/plugins/woocommerce-paynl-payment-methods/