We may ask you to pay extra for a ride you have already paid for once.
When you book a ride far in advance, such as for a vacation, you deposit a balance to pay for it. You may make rides in the meantime. These rides are then paid for from your current balance. Then there may not be enough balance left to pay for your ride in the future.
Therefore, we ask that you make additional payments so that your ride can remain in the future.