I had a similar incident where my radio was knocked out due to a battery change. There was a sheet of paper I received when I purchased the car which served as a check list for the original owner when we drove the car off the lot for the first time. On the top of the page, it had both the radio code and the NAVI code specific to your car. I kept all my stuff in the binder in the glove compartment with all the manuals. Try there. If you are not the original owner of the car, I think the dealership gives you a very difficult time in obtaining the codes.