The booking was rejected. What happens now?

The payment for the associated transaction was cancelled, which means that it was reversed back to your account. In the case of a reversal, you won't see a refund credit on your statement. You will just see the original authorization drop off the statement entirely after a few days. There will be no payment and no refund. It'll appear as if the whole transaction never happened.

Your bank should be able to confirm this. Depending on the card issuer, It may take a few days for the money to reach your bank account.

If you have to make another booking and are still waiting for the funds, you can try to reach out to other providers directly, via message, to confirm availability before committing to a final booking.