If it were me (and I've done this), I'd make a new reservation using the special for your nights through October 30th.
Once you have that confirmation, call and modify the original reservation to cover the nights of October 31st through your November nights.
Even though you can't get the deal for the whole stay, you can take advantage of it for the first 7 nights. That might just be enough saved to cover the last one or two nights.
Good luck!!