Of course, Nicolas is right, and encouraging customers looking at their order listing is vital in this case.
Since I seem to have a similar situation (and you have HS Business as well), maybe do it like me and add a new order status following "confirmed": name it e.g. "confirmed, pending payment". As you're waiting for the customer to pay, you can change the order status in the backend from confirmed to the new status and trigger the customer to be notified, too. He'll get an email, sort of reminding him, and can go to the order listing from there.
Eventually you can - again, like me - utilise a custom field in the order table to add a note or comment which will then show up in email and order under "Additional information".
Admittedly, I'm still "under construction" with this, but so far it works. Good luck to you.