this is so intriguing..i'm so curious and eager to find out..

she probably still has friends in high places :]] ♥ ♥ ♥

I don't know. It is kinda funny she wanted her old body back. Probably just for Dean....

I think the most likely explanation is one of the angels she used to serve with- she probably saved their butt once and asked them to fix her up. Castiel restored Dean's body, right? So angels can do that sort of thing. And I don't think it's surprising that she'd want to keep that body. After all she lived probably 20 or more years in it as a human, thinking she was just human- it probably represents the humanity that she treasures. That's why she fell right? To be human.
I doubt that it was one of the four- they would strike her down in a heartbeat- after all they're the ones who gave the order to kill her in the first place.

My first instinct was to say God, but the angels do seem to have some rather God-like powers, so it's unlikely she would have had to go all the way to the top of the heap. It makes sense that it would be someone she served with, albeit someone very powerful.