I think the tensioner, idler, and cam seals are normally replaced at the 105k miles point. It sounds like the dealer may have messed up. I can understand your disappointment but it may be best to take the offer they made to you. I assume the valves have been now been bent due to the problem. If you do the work needed, you will also have new headgaskets that can also be a problem at times.
Here is a link to a good Subaru site I recommend you should join. There is lots of good help from the folks there on our favorite cars.