Oil change went horribly wrong

2005 Mazda 3 - 2.0L - 4cyl ; 43,000 Miles.

I took my car into a major chain lube shop for an oil change. I also purchased the extra engine clean and fuel system clean package they keep recommending. 3 days later my check engine light came on. I returned to the shop and they advised that there was not a problem, just one of the indicators for the emissions system must have gotten tripped during the oil change and they reset the light. 2 weeks later the light reappeared so I took it to the dealer. Apparently, the fuel cleaner is in my vacuum line and I have an $1100 estimate for a new intake manifold that was damaged. First, is that the fault of the lube shop-and second-shouldn't they be liable? The Mazda dealer certainly thinks so.