I'm wondering if perhaps that copy of the webpage was an out-of-date cached page from a server that hadn't been updated recently enough (or that the page was created based on a copy of data in a cache that hadn't been updated recently enough) and that buying from such a page somehow led to a phantom purchase being created -- since there were no actual phones left to buy -- which got pushed through the system to the point of creating a UPS record for a non-existent phone.
Obviously, one would hope an ecommerce system would catch issues like that so spurious purchases would not be allowed through in the end, but -- in any case -- should the buyer perhaps have realized (in retrospect, at least, if not at the time) that there might be a problem if all his previous attempts to load the webpage were telling him the phone was sold out?