@Corinna76
I do not understand the issue.
First: there are other (better) options available
- If the guest had sent you a change request, the booking (if OK with you) was shifted to other dates, no need to cancel/refund at all
- Now the guest has already cancelled and made a new booking, you can also "refund" the guest by using a change request on the reservation and amend the price.
When this reservation was cancelled: indeed 50% is paid to you after the original check-in date of the reservation and the other 50% is instantly refunded to guest.