I have had the same problem occur just this month. Audi RS7 2021. Similar scenario had a load of warning lamps come on - mechanical fault, slip diff and start/stop malfunction. I called Audi assist even though i have the extended warranty i couldn't use them as i don't have the breakdown cover. I had to use admiral. Car was looked at and the alternator wasn't charging the battery advised to take it to Audi. Car was drivable.
As i prepared for the journey not less than 5 min all sorts of warning lights came up and power just went into limp mode. I was able to park up and avoided an accident. Today i have had it towed to West london audi. Nice chap service - said they would look at the car next week but for now i am without a car.
Fine print - if you have audi extended warranty but not roadside they can't help but if you have both you are eligible for a courtesy car - what nonsense is this.
As this is a known issue should audi provide a courtesy car as i am unsure how long this will take ? I have two small kids and its the summer holiday so not great to be without a car.
From speaking to the service chap the work should be covered but at this stage they have to run the diagnostics to confirm.
Any help ? Those that have been through it did they provide a car while work was carried out?