Can I change the dates on a hotel booking after it has already been confirmed, or do I have to cancel and book again?

Usually no, not as a direct change. Most hotel suppliers treat a confirmed booking as fixed, so moving the dates means cancelling the original booking and making a new one at whatever rate is available on the day you rebook. Some suppliers do allow a date change or a guest name change through the API, but it is not something we can promise across the board, because it depends entirely on the supplier sitting behind that particular rate.

The practical thing to look at is the cancellation policy that came back with the rate you booked. If the booking is still inside its free cancellation window, cancelling and rebooking costs your customer nothing beyond any difference in the new rate, and it is the cleanest way to move dates. If the rate was non refundable, or the free cancellation date has already passed, a cancellation will normally attract a charge, and it is worth asking us to check with the supplier before you cancel, though nothing is guaranteed.

Where a supplier does support amendments, the API will take the new dates and come back either with a confirmation or with a message explaining why it was refused, for example because the hotel has no rooms left on those nights. The booking record is then updated so your staff and your customer are looking at the same information.

Before you promise a customer flexible dates, check the cancellation terms shown on the rate at the time of booking and keep a copy with the booking, so you know exactly where you stand if they later ask to move the trip.