Is it possible to change the date if there is no reward night available on that date?

Also, for other dates showing availibility, they are not actully available if I book it myself. I will have to call WOH to book it. They are refundable until 4 days before check-in.

With that being said, should I 1. call WOH to book another dates? 2. call WOH (or the hotel?) to change the reservation to the dates I want? Have you done it before?