If I am reading you correctly the issue was caused at some point by an expired CC. Disney never contacted you and you saw no effect on your account and rights. You found out the issue existed from information on the renter's side. This took about 8 months for you to learn.
This is pretty much what I would have expected. I don't think the reason why the CC didn't work matters. Here, the expired CC and subsequent charges is 100% on Disney, maybe excluding outright fraud but even then it is a Disney problem imo. You didn't give an opinion on the renter's credit, sign a co pay agreement. Not Disney, not any company nor any person can make someone responsible for what happens in these situations with out express consent. I am far from a CC expert but this seems to violate many federal and state consumer protections. And just like the IL Consumer Fraud Act it acts outside (or despite if you prefer) a contract. FYI sign a contract for murder and see if a court enforces it. then ask why a perfectly executed contract won't be enforced. Law rules contracts.
In addition to my chat with
DVC here is what is on line at Disney now. Notice it covers room damages, smoking etc. Again I am not a CC expert but I don't see how taking an extra 100 dollars every time a charge is made can go wrong. the hold and hold time are not the bill and payment. I am fairly sure Disney also (or did) check on the remaining balance on a card but not how. It might be that damage discovered exceeds the CC max after check out. Still can't see this an owner issue.