I do not know if the model works with the Navigon, but looking at the compatible mobile phone list, the closet modelGT-S5230C it should work.
Turn off bluetooth. Delete the navigon profile from your bluetooth settings, and the phone profile on the navigon. Dismount the Navigon and turn it completely off. Reboot the navigon and mount it to the car. Turn on the bluetooth settings on your phone and pair it to the navigon (from the phone). When its connected try to import your phone book. A bluetooth request pops up on your phone. Accept. If the bluetooth request does not pop up on your phone, it might be because its incompatible. If something else happens i cannot help.
Never cancel the importing process on the navigon, as this creates problems. All sorts of problems.