Brake issue all sorted. The warning indicator for the brakes, relating to the SBC (Servotronic Brake Controller) has been reset by an independent Mercedes garage. Merc will only replace the unit (€600 from Bosch, who make them, or over £1000 from Mercedes plus fitting). The light is activated by the number of times the brakes are applied (rather a lot in a car with over 300,000km on the clock) and as Mercedes themselves told me, they have no information to suggest that the re-engineered part installed on recall will fail again. This added to the information that if the system does fail, it just operates like a normal servo-assisted braking system, means that I'm as happy as I'm going to be with the situation. Even if it cost me half the €500 bill to reset the system.
No info on the phone setup though...