If my customer wants to change the dates on a hotel booking they have already made, can I do that in the system or does it have to be cancelled and booked again?

In most cases it has to be cancelled and booked again, so no, a date change is usually not a simple edit. The reason is that the date is part of what the supplier priced in the first place, so changing it means a different rate and a different availability check. Most hotel suppliers do not accept a date change, a room type change or a change in the number of guests through their API at all, and the only path they offer is to cancel the existing booking and make a new one for the new dates.

Smaller changes are often a different story. Correcting the spelling of a guest name, updating the lead guest, or adding a request such as a late arrival note can sometimes be sent to the supplier after the booking is confirmed, and where the supplier supports it that can be done from the booking screen in your portal rather than by email. Whether it works and how quickly the hotel acts on it is decided by the supplier and the hotel, not by us, so it is honest to tell your customer that the request has been passed on rather than that it is done.

Before you cancel anything, the cancellation terms matter more than the booking screen does. If the rate is refundable and you are still inside the free cancellation window, cancelling and rebooking is usually clean, although you should expect the new dates to carry whatever rate is live that day rather than the old one. If the rate is non refundable, cancelling means your customer loses what they paid, and the only option left is to ask the supplier or the hotel for a goodwill change, which they may refuse. Hotels you have contracted directly and loaded yourself are the exception, because you control those terms.

So open the booking in your portal, read the cancellation policy and deadline on it, and check with that particular supplier what changes they accept before you promise your customer anything.