FWIW: I had to change the dates on an award ticket, something that was not possible the do online.
Dreaded the phone call and had very low expectations.The call took about 40 minutes total, of which approx. 30 were wasted on hold, on advertisements and announcements.
The call to the 801 number (who would have guessed ) was routed to the Philippines and the quality was terrible.
However, assistance was remarkably helpful and the agent - with a heavy accent - competent, professional and courteous.
No fees were charged for the change.