A couple of thoughts on this.
First, VRBO is essentially just a classified ad marketplace. They don't control any of the listings directly, or manage inventory. They are just a marketing outlet for private owners to offer homes, condos, or timeshares for rent to individuals. They do take some steps to make sure their owners are legitimate, but they are not perfect. So, "VRBO cancelled the reservation" is hogwash.
So, if it wasn't VRBO, what happened? It is very likely the owner's fault. About the only way an owner can make any kind of decent return renting time at Bonnet Creek is by being a VIP owner and being able to book units in the discount/upgrade window---this ranges from 30-60 days depending on owner type. Many owners will book units outside this window at full points, and then when they get closer to check-in, re-book the units to take advantage of the discounts. But, to do this, they have to cancel and rebook the unit they have unless there is extra, unbooked inventory. Most of the time, this works just fine. But, every once in a while, someone else will snap up the unit between the cancellation and rebooking, leaving the owner with no reservation.
The reason I think this is the most likely outcome is (a) many VIP owners on timeshare boards have reported that cancel/rebook has become more chancy and (b) these "mysterious" cancelled Bonnet Creek weeks only seem to happen to renters, never to owners directly. This latter point makes me think it is not some inventory management problem on Wyndham's end.
So, the upshot: if you are going to rent from a BC owner, it is very important to rent from well-known, reputable sources. I'm an owner myself, so I just book time directly. But, if I were renting, I'd rent from one of the big consolidators: Ken at Vacation Upgrades, the folks at Vacation Strategy. There may be one or two others---I haven't followed the market closely. These sources might be a few dollars more than Joe Random Owner on Ebay or VRBO, but those few extra dollars are probably worth the peace of mind.