It will depend upon where you acquired the ticket. If the ticket was purchased directly and separately from Disney, they can essentially refund it and sell you the new ticket that you want. If you purchased from a third party or as part of a package, then the cannot upgrade it over the phone; those tickets can only be upgraded/exchanged in person.
(We’ve seen one person who claimed to have been able to upgrade a third-part my ticket over the phone, but the claim was not substantiated. With Disney adding the ability to upgrade tickets in the app, maybe it will be possible now or in the future)