During the few months I've been working with signatures with woocommerce plugin and billet, have received complaints from my clients who would be making the payment and I have not brought about the sale, but I did not receive input through my bank. I checked and found that after generating ticket and print bar codes were modified.
My site is getting high connections and several canceled orders. I use https security believe that before long other websites and users that use this plugin will have the same problems.
Claudio wise counsel, great collaborator revising the codes and add transformed straight to PDF instead of printing html. Thus gain time to protect our systems and long life to wordpress.