Similar certificate issue... Called in several months ago to make a 2-night reservation using the 2 oldest certificates. When the confirmation e-mail arrived, an incorrect certificate had been used, so called in and they said it would be corrected and the stay occurred without issue. However, when I recently called in to use the remaining certificates, was told I am short by one. Turns out the correction did not remove the "used" designation from the certificate that should have been kept for later. The phone rep was able to verify the error when I supplied certificate numbers, but said it would have to go through an investigation process before the cert could be used. Am still waiting for resolution, and this thread is a good reminder that I should follow-up.