I am trying to add the following to my already ticketed award (EWR-BOG), a one way flight and I am doing it within 24 hour cancellation window.

Excursionist perk( IGU-EZE) same region and it is coming out at 0 miles and taxes

last leg: taking a return flight from IST/LIS- NYC later this year for another trip.

Eveyrthing is calculating fine except when I go to last page for payment, the website bombed.

should I call and see if there is an availability issue OR would I be making life difficult for an agent?

ETA: I was able to get it ticketed online.