I'm having a similar problem. A guest cancelled due to passport problems (she waited too long and then didn't want to pay for an expedited passport). The thing is, when she cancelled, she just assumed I would issue a full refund, no questions asked, this despite the fact she is a host herself and so understands what a "strict" cancellation policy means.
Because of her attitude and her griping messages (wherein the passport problem became something that "happened to her" rather than it being her poor planning), I decided not to offer her a future voucher. Also, I'm wondering if someone books for 5 days during low season, and then wants to change that into a high season booking, would that mean that the dollar amount would then be worth fewer days? And how does one work that out?
The days are coming up in mid April and I have not had a booking to replace them yet. She is pleading all sorts of domestic reasons why I should return the full amount, which is just making things worse for me...her poor planning isn't my problem but she's using every guilt trip in the book, along with suggesting she gave me ample time to find other guests. But the fact is the days are still not booked.
I'm not sure what will happen, but I want to stand my ground here. I'm having a hard time taking in the fact that this woman is a host herself. April is not high season in Montreal, although it is on the cusp of it.