A new one can be had off Ebay for 400 pounds, and installation is a 2 minute job, so at least don't go the 2K stealer way! As for repairs, sorry can't help.
I've managed to track down a new unit for under £400. It comes with the latest software as well. I spoke to Autosonic in Aberdeen who did a brilliant job repairing my old Meridian Hifi amps, but as BMW won't provide the info on circuts etc they couldn't really help.
