If the change is made before departure from the pick-up point (before the actual vehicle), the pre-determined fixed fare can be cancelled and switched to a meter fare.
However, if the change is made after departure from the pick-up point, the full amount of the pre-determined fare (the full amount of the fare to the pre-determined destination) must be paid at the time of the change, and then the meter fare will be switched to the meter fare from the point of change. The departure point of the metered fare will be the changed point. Please understand this beforehand.