Phil wrote ...

OK.. brand new C4 yes?

First of all disconnect the car's battery for a minute, then reconnect.. then Ignition on, engine off.

Second, make sure your phones bluetooth is turned on and discoverable.

The key is to make sure all the searching/ pairing is done from the car (as opposed to searching/ pairing from the phone). If you pair from the car, it will give you random number to enter in your phone to complete pairing. When request appears on your phone to enter number, enter number given and press OK.

Hey presto... " pairing success" should appear.

Don't ask me why you have to disconnect the battery, and be assured, you won't have to do this again for future pairings.. just seems to be something on initial setup... we've had 3 DS3's now with same problem, all cured using this process.