The original records are actually the property of the doctor or hospital that took them in the first place. You've a right to a copy of them. And as you've signed a release, you should have them. The other doctor may have a better chance at getting them though. I'm going through the same thing right now, trying to get my previous c-section records from archives. Maybe my case is different, because they're military records, but it says clearly on the letter sent with them that the originals are government property and I can only get a copy.
Hope everything works out for you.
alleusion on Ravelry
...I can't have too many projects, I still have empty needles...