I have retrieved mine from my local independent VW/Audi/Skoda/etc specialist following a complete failure of the battery.
As I have mentioned elsewhere, I suspected that the front and rear cameras of my MiWitness weren't being put into "sleep" mode by the gizmo which is supposed to monitor the battery voltage and turn the cameras off when the battery dropped below 11 volts - the camera system has a parking mode, and will capture movement when the car is parked.
Having tried and failed to revive the battery with a CTEK battery charger/conditioner, I had to resort to my rechargeable pocket-sized battery jumper, which did the job of starting the car, after several error messages had flashed up - ACC, Stop/Start, parking brake, auto hold, you name it.
The battery was put on charge in the workshop, tested, and declared to be toast, as expected. They (Abtech) only fit genuine batteries these days, due to compatibility issues with aftermarket and pattern batteries, and once this was fitted, and all of the error codes cleared, all is well again.
The original battery was five years old, and as the car has Stop/Start, has probably had a hard life, and these things happen. At £284, I'm hoping for a good few years from the replacement.