Getting a transciption from the MNC.

I need a transciption of my training in St Richard's Hospital, Chichester from 1974-1977, in order to work in California, USA. I've been working as a nurse in Florida since 1994, but this is not good enough for California. I've sent e-mail to the MNC but they say there's no guarantee that they can find them. My job is in danger, does anyone have any advce for me?