Customer to be able cancel his pending/unpaid order.
Some customers they make an order, they don't pay it because he change his mind to order another product/service, and they don't make a new order because they are afraid the payment will go to the first one placed.
Daily we got around 5-10 calls and emails because of this and around another 5 for the upgrades.
I do propose to add to the client area an cancellation order button or something. Customer make the order, he dose pay it to be able to cancel it and not to call us or email us.
If he got some money on the invoice but not enough to pay the bill to notify the customer the amount had on the invoice it will be added to his client area if not just to cancel it.