We noticed that if a PayPal or some other hosted gateway payment is canceled Magento still goes through the checkout, but leaves the web-to-print order as “pending”. The problem is that our web-to-print code doesn’t differentiate by status – anything that goes through the checkout is processed by ZP, PDF files generated and the billing flag is set.
We cannot charge customers for web-to-print orders they don’t need, so an update is coming in the next few days. See our issue tracking for more details.
The other option is to install an SSL certificate and process credit cards right on your website.
Contact us if your web-to-print site is being affected by this issue. We should be able to remove those web-to-print orders from your billing. This was never our intention to charge for unpaid orders.