I have a 2003 A6 quattro that I purchased last August that now has 80K miles. I have begun to experience problems with my central locking system. The remote key quit working. I can still manually lock and unlock the car with the key, just not with the remote. I tried to use the spare key remote and it would not work either. I then bought new batteries for the remote keys and still no go. What do I try next? I miss using the keyless entry. I am fortunate that everything with the central locking system still works perfect except for the remote control keyless entry. Is there a receiver for the remote that needs to be checked/replaced? Does the main control unit need to be replaced? I don't know where the receiver or control unit are located. Any help would be much appreciated! This car rocks and I have not had any other problems! Thanks