I've had to change my reservations before the tickets were mailed. There was no problem. Then the tickets were mailed (the trip was over 3 months away, so they said they had to mail them ) and I had to cancel the trip. I just mailed the tickets back to AGR and, (IIRC) within 2 weeks, the points were redeposited into my account! ^

No problems! (And no "service fees"! )