Update from me as promised for this group.
Took the a3 Sportback in today to local Audi dealer - who confirmed that there are issues with the MMI software.
They carried out an investigation into MMI issues - in my case this was manifesting as the MMI not storing radio favourites for more than 3 days, after this it reverts to 88.3mhz. (- a random frequency). And the set up wizard then typically returns and asks to set up the system again every 3 days.
They have confirmed the issues are with the MMI and found relevant information from Audi confirming the fault.
The current advice from Audi to the dealer is to postpone a repair fix until this fix is due for release in December 2024.
so this is the very latest advice hot off the press today - 09 August.