Q3 Q3 Corroded rear discs

Has anyone had an issue with a Q3 having badly corroded and pitted rear discs. Wifes Q3 which is 2 years old in march is in getting a bit of warranty work done (something broke between steering wheel and steering column).
Anyway car has just over 12k miles and I got a video today saying it needs new rear discs due to the corrosion and pitting. Anyone else had this and had any luck with it under warranty. Still waiting on service guy calling me back. I know they are probably going to use the old wear and tear thing but in my eyes a set of rear discs should last longer than 2 years and 12000 miles.

Doesn't seem quite right to me either waiting to hear what they have to say, they are giving it as an advisory just. They can stay as they are until it goes back when the lease is up.