I'm not sure what a "waitlist service" is but I have had good luck with the Touring Plans reservation finder. Basically it notifies you (via email or text) when a reservation meeting your specifications becomes available but it is up to you to log in to the WDW site or My Disney Experience and book it yourself. It does not make the reservation for you or hold it. Depending on how popular the place is, you have to be prepared to jump on it right away when you receive the notification. I've been able to secure several reservations I wanted using this. But I've also had some that never materialized and have also had times where I didn't see the notification in time and someone else had snatched it up. Patience is key. And I'd recommend continuing to check yourself from time to time vs. 100% reliance on the finder. Good luck - hope you are able to get what you're looking for!