To prevent this from happening again, you really need to be in touch with the resort and the managing company/resort sales company throughout the entire closing process-question everything. Then you can catch things and ask questions as the process moves along. In short- you have to be a pain in the "you know what". Assume whatever can go wrong will go wrong so you will leave no stone unturned. The estoppel might not say it's a points program, but you still get on the phone and verify- "is this a fixed week or a points week?", etc. Be paranoid! After the closing, call the resort- I have guests coming- is everything all set?
When I closed on mine (I didn't buy on EBAY, though)- during the whole process I was emailing and calling the transfer company, the resort mgmt. company, the resort sales company that was handling the transfer. After the closing I verified I was in the mgmt. company's system so I could go on-line to see my account and also sign up with VRI*ety to do exchanges. I called the resort to make sure my unit was reserved for this year, even though I could see it on-line. Sometimes I got wrong info. or could not get a hold of the right person. I still persevered! You have to cover ALL bases!
By luck, after joining the OWNERS (of the resort) Facebook page (another good idea) I learned that even fixed week owners at the resort have to fill out a usage form every year to indicate whether or not they are using their week, renting it out or want the resort to rent it out for them, exchanging it with RCI, II or VRI*ety, sending a guest, using it as points (if you own points), etc. I would have never known about it if I didn't join that Facebook page.