Brake Abs Warning Light problems of the 2002 Mercedes Benz C320

Was driving on highway when esp, bas and abs lights show up, and speedometer display stops working - speed reading goes to zero, though there is no reduction in speed. Get to destination. On return it happens again. This time I go to rest area, stop the car, remove the key and restart. The car refuses to move out of park. Call roadside assistance and get instruction to override park, drive home with flashers on - very rough ride quality. Tow to dealer next day, they are not sure if new part will fix it, even if $1850 part is replaced. Lots of electrical problems over the years. Turn lights go out routinely. Changed cd changer. Seat drains battery,had to disconnect it. Poor electrical sensors all around. Now it also has rust damage, all of a sudden, at the bottom of doors.