I bought my current camera (Nikon D70) in May 2004, just a few days after that model started to appear in shops. I made several thousand photos with this camera and I have been happy with the results… Until a few months ago, when it started behaving in a strange way: sometimes the camera would take unusually long to power up, sometimes it would appear to work correctly for a while but then suddenly start to display bogus exposure values. Without moving the camera or changing the lighting conditions, it would randomly change between 1/500s and 2 seconds, or some other very different values. When the camera started to behave like that, it was almost impossible to shoot anything with the correct exposure.
Over time, this problem became more and more severe so I eventually decided to bring the camera back to the shop for repair. My camera was 3 years old, so the warranty had already expired. The guy at the shop asked me to pay 50 EUR in advance and told me that he would send it to Nikon for repair, without expecting too much: regardless of the brand and model, many cameras are just returned because repairing them would cost more than a new model. This is a bit annoying when the camera costs around 1000 EUR.
Two weeks later, I got a letter telling me that my camera was back in the shop. The letter did not mention any repairs, so I was a bit worried. I went to the shop to pick it up and I had a pleasant surprise: Nikon replaced the defective circuits at no cost. When I tested the camera, I found that they also upgraded the firmware to a newer version, which includes new features and fixes some bugs that I had encountered before. And they also cleaned up the camera (inside and outside). So this is a happy end. Thanks to the Nikon customer service!