Guntor

I took delivery of my new Q7 e-tron in October and got the Audi Connect working with the help of a data sim-card in the slot in the glove compartment. It worked fine, however with occasional "connection to the car available" error messages, which were unrelated to poor coverage.
Since 23 December, however, the connection to the app is completely gone (otherwise Audi Connect works fine, however) and has not returned despite all kinds of efforts (replacing the sim card, logging in and out etc). According to the My Audi page I am registered as key user and the vehicle is connected, but the Audi Connect user administration in the car keeps producing error messages and says that no user is registered (nor does if let me register new users).
Has anyone had similar problems?
As a sidenote, the app was updated 22 December. Could it all be due to a bug in the new software? If so, this (and the delay in fixing it) is totally unacceptable.
The dealer has not been able to help.