Yes, I had a guy mistakenly make an online purchase of a downloadable item (£60) twice. This was his fault. Instead of contacting us he put a charge back on both purchases. He had the item and we had nothing but hassle. It took about three months for PayPal to return what we were owed.
Having said that, if a guaranteed delivery time was part of the conditions in (2) above then that guy may have a case?