CEL Soap Opera

I couldn't get my VW inspected because it had a lit CEL (emissions testing FTW). So I took it to the shop and they checked the code and replaced the oxygen sensor. They said the system would reset after about 50 miles, but it didn't. So I took it back to the shop and now they're saying its giving a catalytic converter fault code. Which is interesting, because I thought the CC had self-destructed years ago, but the car always passed inspection. UPDATE: As I was typing, the shop called back and said the CC needs to be replaced, cheapest he can do it is $675. Fuck.