I as well had a problem with my 2001 C320 key’s. I brought it up to the dealership and they took care of it by ordering new keys for it. But still I have been getting problems with the system. Some times the key will not lock the car; or it will not adjust the seat, mirror’s, and steering wheel. I am thinking of bringing up the problem next time I visit the service department. Do you guys think that my EIS is bad?