Second Service Appointment For Check Engine Light- Opinions Please

I had a check engine light come about 2 months ago. They said it was a turbo recirculation vavle or sometihing. Even thought the order receipt said sollenoid (spelling). They had to order the part, so I had to come back a week later. I went back and they installed it. About a month later, my check engine light came on again. I called back - the first thing the rep says to me is "...it is not the same problem..."
I am getting suspicious. First, what they said was wrong was not on the invoice order sheet for the first service visit. Second. the first thing the rep tells me is that it is not the same problem, even though she obviously knows nothing about my current problem or my previous problem off hand.
I have an appointment 12/5. Should I be skeptical about the first problem and the reps quick comments? Secondly, if it happens again should I demand a rental to miss a third day of work for a check engine light?
I purchased and servive at Russell, in Baltimore, MD. So far they have been great. But, I now wonder. The reps comments really made me think.
Don't get me wrong, I love my VW. I just want what is best for it.
Thanks.