Last spring I bought a Windows XP Professional PC with a free upgrade to Windows Vista Business. I filed the required paperwork for the upgrade, supplied credit card information to pay for shipping and handling, and received a confirmation e-mail from ModusLink (the company that handled the Vista upgrade program) stating that the software would be shipped in four to six weeks.

Nearly two months later, I checked the ModusLink site and found that the order had been canceled--because, I suspect, the temporary credit card that I had used to pay shipping and handling expired (I had set it to last only the four to six weeks I was told it would take to get the upgrade). I would have reapplied, but by then the upgrade program had ended, and calls to ModusLink were fruitless.

--Mitchel Miller, Cookeville, Tennessee

OYS Responds: ModusLink told us that Miller was correct: The Vista upgrade was delayed for so long that his temporary credit card number had expired by the time the company was ready to charge for the shipment. ModusLink says that in this situation it tries to reach customers by e-mail, and Miller did hear from the company but was unable to get through on the phone to provide a new card number. After we spoke with ModusLink, Miller was able to contact the company; he received his upgrade at the end of June.

ModusLink says that it processed Vista upgrade orders for several major PC vendors, including Dell and HP. That program ended on May 31; the company says that people whose orders were canceled (typically because they did not have valid cards) should contact their PC manufacturers if they have not already done so.

We recommend against using limited-duration credit cards to pay for services or products that might involve a waiting period. Companies shouldn't charge for services or goods until they are ready to deliver them--but that consumer protection can backfire if the card you use expires before the vendor submits a charge.