I am astounded by your experience wih this rescue group, you did all of the right things checking them as well as you could and to have them treat you and your Oliver like that is disgusting.
I understand the reason for the mods to take the name off of this as it could lead to a law suit. IMO maybe the law should look at them.
After reading all of the wonderful and yes sometimes sad reports of abandoned pets that the good Resues take in and try to rehome the one you speak of should not be running. pbp
It Is What It Is