If I was in the OP's place, I'd call Canon Service back and ask them on what basis they determined it was an impact damage. It is a fair question to ask. In fact, I'd write to them so I have a record of their response.
I can understand being frustrated by poor customer support and wanting to vent, but this is what I'd have done before (and in addition to) expressing myself on this forum. My 2 cents.Perhaps the pragmatic lesson is to become a CPS member if you own enough equipment to qualify.
I have enough equipment, and believe that $ 100 to be well spent, but unfortunately I don't make any money from photography to qualify.
sell some boudoir photos of your neighbor to your wife. done.