2006 Passat vacuum leak

Car in question: 2006 Passat Luxury 2.0 T bought used from dealer in Aug 2009.
Anyone out there with insight into the following scenario?

First time getting gasoline, check engine light on dash came on which, according to manual, meant I hadn't clicked gas cap fully in place. I took the car back to the dealer. They took the car into the shop, cleaned it up, and some patronizing service dude told me I hadn't clicked the gas cap fully. And wow, guess what? The check engine light was no longer on! I took it back a week later because of the same problem and because a headlight was out and the driver's side sun visor had broken. Service dudes told me dash light meant car had a vacuum leak related to the gas cap and to make sure the cap was on tight. And again, when they turned the car back over to me, the check engine light was off.

Now I've found out from my mechanics that I used for years when I drove a Subaru that TSBs were issued on this car in 2007 indicating the gas cap needed to be replaced and also that a vacuum supply line needed to be replaced due to a sub-sized interior diameter. The car is now leaking oil from the engine. I haven't had time to research other TSBs.

I am taking it to the dealer tomorrow morning because my reliable mechanics don't want to get into the engine. I feel this dealer should have replaced these parts before selling the car. My pal Barry, a mechanic, says because the dealer never solved the check engine issue to begin with, they are obligated to solve the problem even though I have had the car 5 months now.

BTW the trunk latch on this car also broke when I had had it 4 months (part alone was $140) and another headlight went out. I had my reliable mechanics do this work because I don't trust the dealer. I almost got a ticket from a state trooper for the windows being too dark, and it was vandalized two weeks ago, costing me $350 to replace two windows. I'm starting to think someone died in this car and a hex was placed on it.

Thanks for any comments. -- Wanting my Subaru back

yes I agree the dealer should repair this for you at their expense you are probably getting computer code p0455 fuel vapour system gross leak, I can see the dealer turning you away for this condition once and telling you to keep your gas cap on tight but if when they clear the code in the computer and send you away and the same code comes back a week later you definetly have a vapour leak in your fuel system wich needs to be pressure tested to find out where the leak is. it could be a bad gas cap, broken vapour line, fuel tank not sealed up properly anything that would cause the fuel tank to leak vapour. sometimes an ultrasonic leak detector and a smoke machine come in real handy if the dealer has them they might be able to find the leak real easy. cheers!