In this situation, the main reason is usually that the client reaches the final “Booking Overview” page on your online booking site and assumes the booking has already been made. In reality, though, this page is meant as a final overview and review step, and the client still needs to click the “Confirm Booking” button at the bottom of the page—only after that is the booking actually created.

You can also always be sure that when a client actually completes a booking online, you’ll receive an email notification and the booking will appear in your calendar, and the client will likewise receive a booking confirmation and reminder email (provided you’ve enabled those emails).

If the client can’t show you those emails as proof that the booking was made, and you didn’t receive a notification or see a booking appear in your calendar, you can be confident this is simply a mistake on the client’s part.

To avoid situations like this, we recommend going to Apps -> Online Booking -> Preferences -> 6. Confirmation -> “Should the client be shown a booking confirmation page?” and changing it from “Yes” to “No” -> Save & Close.
‍
In that case, the booking is confirmed immediately once the client clicks the button to move to the next page after entering their contact details, and this situation can no longer occur.