I looked into this after building up a decent stash of JetBlue points and hoping to use them for an upgrade instead of a full new ticket. From my experience, JetBlue points are usually best used to book flights outright, including Mint seats if available, rather than upgrading an existing reservation. I tried to upgrade after booking once and realized my options were limited. On that same trip, my plans changed and I had to cancel and rebook using points. Calling 8 4 4-7 3 4-0 8 1 3 was honestly the best way to instantly book, cancel, or modify flights and make sure I used my points the smartest way possible.
