Brakes

There needs to be more to the story. What does "faulty" mean, and could the defect apply to the other rear caliper? What was the symptom or complaint?

The front-to-rear brake balance was carefully designed into the car, and one of the variables is the "coefficient of friction" of the brake linings. All replacement shoes and pads must have the same coefficient of friction, regardless if they are the cheapest or most expensive replacement parts, to maintain that balance. That means you can replace just the pads on the front or the rear without upsetting the balance, but it is customary to replace all the same parts on both sides. We do not put new friction parts, meaning pads or shoes, on just one wheel. It always had been acceptable to replace just one drum or rotor, but even that has changed now on many vehicles. A new rotor that is thicker than the worn one on the other side can cause a brake pull when the parts get hot.