@Deb84, did the extra fee include preparing an extra room or bed? If I had to do work, I would not refund.
As said by someone, it concerns people booked, not who actually stayed. And the announcement after you can check it, is a bit late. To get a train fare back, you have to cancel before traveling day too. (If it's refundable)
If you believe it, if they were great guests, you can give a token refund. Or offer a reduction on the next trip.
I suppose, if you refund everything he asks, he will play the game every time he travels. Does not hurt trying...