Add payment method to Billy PDF?
Go to the template directory of Billy PDF (commerce_billy/modules/commerce_billy_pdf/templates) and copy the file

commerce_order--commerce_order--pdf.tpl.php


to your theme directory. Thats the template of the generated pdf. You can simply edit this template and add the billing method i think.

You can access the order object via 

$order = commerce_order_load($variables['elements']['#entity']-&gt;order_id);


inside of the template.