Hi I took delivery of a new A3 a fortnight ago and have used it daily since then.
I’ve had the SOS warning twice, and the pre-sense apply the brakes once for no reason, but on almost every journey, at least once, the MMI goes blank for 30 seconds or so and shows the message ‘please wait, updating user information’.
i haven’t gone back to the dealer yet, but having read your post I guess I’d better.