Sounds like you need to take the car to a Citroen dealer Sarah as it sounds like the PCM module which controls the central locking is kaputt. What you can do is to disconnect the car battery, after you have made a note of the radio code, and reconnect it after about 5 minutes. This may clear your problem but more than likely not. If the car starts OK then the remote key is fine.
Chris
September 2007