Second-hand exhaust pipe placed on car

I went to the Dunlop in Hillcrest to get my car exhaust assessed. After a 20 minute check they informed me that I would need to have all 3 boxes replaced (the back 2 very badly damaged and the front one would need to be changed in the next year), and recommended that I also have the connecting and end piping changed. I agreed and after a further 20 minutes they informed me that the did not have stock of the front silencer, but said it didn't need to be changed urgently. They informed me that the replacement of the 2 back boxes and the piping would take 4.5 hours, so I left my car there and returned at the time they said. As I arrived they were driving my car out to the parking lot and as a precautionary measure my partner requested that they place it back on the ramp so he could see what they had done. It turns out they had put a second-hand exhaust pipe on my car, despite charging me for a new one. The manager had the audacity to try and convince us it was new, despite the clearly visible rust and damage. After complaining, they agreed to replace it with a new one, but I had to return the next day and leave it there for an additional 4.5 hours. Absolutely SHOCKING service.