When you make a booking, if the certificate is valid, it will automatically be offered to pay for the night (cat 1 to 5). I made a booking slightly pass my current certificate validity, and it was not offered as an option (only the 25k points).

That's okay. I will extend the cert closer to the stay if needed and then swap the points for cert (must do by phone if you don't want to cancel and rebook). But even the stay itself is iffy, so I rather have it locked to points I can easily revert/return and have the cert not stuck and available for use on another potentially near-term stay.

Rasheed