Thank you. It appears that despite them confirming they had attached my certificate, it was not attached at all. I could tell because my certificate was still showing up as "unused" and my reservation showed my points due as 1,147,000 points.
I called again, and they attached the certificate successfully this time. It has now disappeared from my certificates available. My reservation now says "this reservation has an e-certificate" total points for stay: 165,000. A NC 6 is "worth" 165,000 points. So does that mean the certificate is all that is required, or that I need to pay with the certificate and an additional 165,000 points? Specifically my reservation looks like this:
Room Total Summary
165,000
Points
Redemption with Points Upgrade
1 room(s) for 7 nights
- Wednesday, XXXXXX, 2019
- 121000 points + Free Night
- Thursday, XXXXX, 2019
- Friday,XXXXXX, 2019
- Saturday, XXXXXX, 2019
- Sunday, XXXXXXX, 2019
- Monday, XXXXXX, 2019
- Tuesday, XXXXXX, 2019
- Total points rate
165,000
- Estimated government taxes and fees
Included
- Total for stay in hotel's currency
Taxes and fees + 165,000 points