The Volkswagen dealer fixed the problem with the indicator light under warranty today. When I collected the car at lunchtime (sadly not cleaned this time) the service assistant said that it was pretty unlikely to have been a bulb, but they had to let me know that it could be a chargeable item if it was. In this case they replaced the whole indicator module.
Now the only mystery to solve is quite how the radio keeps retuning itself to 210FM whenever the car goes in to the dealer. Do they have a deal with the radio station or something? 😉