Take a look at this thread. A fellow members had a similar issue 5 days ago.
https://www.audiownersclub.com/forums/topic/24553-bench-test-dash-cluster/
dpf and egr are the biggest risk factors. The after that turbo and injectors.
However well serviced diesel's can last along time.
My a6 c5 2.5tdi has never missed a service from new and been over serviced if anything. Before engine went bang it had covered 344k miles.
It was on its second turbo and original injectors.
I'm putting a replacement engine in it now.
You'd think a loose caliper etc would have been picked up once brake were changed.
Could it be a wheel bearing (even though this would be a rumbling sound normally) or a driveshaft issue?
I'm assuming tyres have been checked too.
Garage has to fix this foc in the first 30 days after purchase. You could get an alternative opinion from another garage incase the supplying dealer is trying to fob you off.
If it all comes from the same car then you should be ok I think. The only problem is, the mileage for your car would be wrong. In my opinion you'd be better getting it all coded to your current cluster
I've never heard of that before (ignoring the failing module). I'd recommend an Audi independent specialist might be best. Please keep us posted on how you get on