Needing a bit more information...

Have you purchased the ticket online yet? Or is the reservation on hold on aa.com?

Upgrade from what standpoint?

Upgrade a booking from a G fare to a W fare which has less restrictions?

Upgrade from Coach class seating to Business Class seating with miles/copay?


On-hold reservation . that you want to change the fare basis . call Web Services.

Ticketed reservation you want to change to a different fare basis .. call aa reservations.

Ticketed reservation you want to use miles/co-pay on to upgrade to a higher class of service .. call aa reservations. This is harder since the inventory for the upgrade must be available or you will go on standby upgrade list. AND the co-pay is not refundable should you not confirm...

aa.com is pretty limited in add/collect features. You cannot use a paper voucher to part-pay a ticket...