I had 2 certs (one expiring November 1, 2022 and another expiring December 31, 2022). I called in to make a 2 night reservation at Conrad Koh Samui for early December fully knowing one of them would be expired for this trip but played dumb on the phone and spoke to the agent very politely. They told me one of the cert would be expired and that they've already extended the cert before and wouldnt extend it again but was told to be put on hold. I was on hold for maybe 10 more minutes and the rep told me as a one time gesture she would extend it for me. so she updated the cert's expiry date to late december and was able to make the 2 night booking for me!