@Patsy4 I used to trust people until they proved themselves to be untrustworthy. But after getting burned by oh-so-sincere people who didn't follow through on what they promised, I now no longer trust people until they prove themselves to be trustworthy.
I'm not sure how you expected them to be charged or pay, though, if you didn't extend the reservation? Were they just going to pay you cash for the last 3 days? If so, I would have gotten the cash up front before allowing them to extend.