Q: Breakes. Hard Pedal. Rear breaks do nothing. on 1990 Jaguar XJ6

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The break pedal is extremely hard, and upon inspection of wheels, I discovered the rear breaks are not working at all: rust has accumulated and the disks and wheels remain cold. I am clueless as how to proceed to repair my car's break system.
(1) Answer
You need to have a repair shop diagnose exactly what parts are needed and you can find a shop here and double check repair prices here