Refund

[Luis49]

I had to cancel a guest´s instant reservation because it presented conflicts with dates from another company´s guest.  As this happened before they checked in, I did not receive any payment.  Yesterday, the guest wrote to me asking about the refund, as they had not received back the money they paid with the instant reservation.  I asked them to write to Airbnb directly.  Is this right?  What happens in these cases?  Luis