I was using some credit card rewards points to book a flight YYZ-JFK in January; it booked on Delta using a Westjet Codeshare. Am I correct in assuming that since I don't see it in manage my booking on delta.com I can't pay to upgrade this to first until time of check in (if available?) Put another way if I call Delta and put up with the wait is there a way to pay the upgrade if speaking to an agent?