Can I change a hotel booking through the API if my customer wants different dates or a different guest name?

Sometimes, and it depends entirely on the supplier and on the rate that was booked. Some hotel booking APIs offer a proper amendment request that lets you send new dates, a different room, or a corrected guest name, and the supplier either accepts it or turns it down. Others offer nothing of the sort, and the only way to change anything is to cancel the booking and make a new one.

Even where amendments are supported, a change of dates is really a new price request, because the room you now want may cost something different or may not be free at all. That is why an amendment can come back refused even though the booking itself is perfectly valid. A simple correction such as a misspelled guest name is usually the easiest kind to get through, although some hotels still want it done by hand at their end.

Cancelling and rebooking sounds like the simple answer, but it carries a real risk, because the old booking may already be inside its charge period and the new one may not be available at the same price. If the rate was a non refundable one, that route can be expensive for whoever has to absorb the difference, so it is worth checking the cancellation terms on the original booking before you touch anything.

Before you promise a customer a change, look at the rate terms on the booking and ask your supplier which amendments they accept through the API and which ones have to go through their support team.