help flooded 328

My 328 has just been flooded in an underground garage in the south of france. There was around 35cm of water at the front and 30 cm to the rear. It appears to have been just below the exhaust pipes bou may have reached the fans at the front. The car starts and will drive. The main problem is dirty water in the interior. I'd like to take her out for a long hot drive to dry her out but my garagist is worried about grit in the fans and possible water in the gearbox. The seals between the motor and the gearbox were replaced last year. Is water ingress likely to be a problem and is there anything else to lookout for? There is a danger of the French insurance co writing her off, which I want to avoid. Any help appreciated.
GG