casewindow:
[snip]...
They said the rear rotors are too rusted to pass a warrant.
.....
Do you use the vehicle with any kind of regularity? If so then I don't buy this.
A vehicle would have to be sitting unused for a significant amount of time for rust to build up on brake rotors to the extent that it would required replacing.
Every time you drive a vehicle the brakes are cleaned.
If DIY is not your thing then definitely get a second quote.