Modification Refund?

Guests booked in Oct 2024 the whole month of June from the 1st to the 30th. They just messaged asking to modify check out to the 21st. Apparently VRBO does not consider modifications as cancellations, therefore, the cancellation policies don’t apply. That’s over 2k I’d have to refund on such short notice. Other than changing the 20% month discount to a 20% week discount, I’m not sure what to do. 😡 not happy

Any suggestions?