My 150PS petrol estate has just had its first variable service at 15,000 miles - it is nearly 2 years old.  On the service report, it shows pad thicknesses of 9mm front and 7mm rear, but what surprised me was a note to say that the rear discs were worn and that replacement should be considered.  That seemed odd so I queried it but didn't really get a conclusive answer - just that they were worn.   It's under 2 years old, has done 15,000 miles, I don't live near the sea (or any other po