Took my A5 cabrio in due to rear defrost not working. Tech found "no applicable faults". He further noted "client should understand that the emergency management system in the vehicle will prioritize certain functions over others, such as recharging battery and operating climate control before secondary functions such as de-foggers. This is avfeature of the vehicle to always ensure enough charging energy is applied to more critical functions of the vehicle. Does this sound right? I would think the rear defrost would be a critical function.