So heres the story: I was driving my 91 civic back from work when my
check oil light came on. I stopped at a gas station, got new oil, and
went on my way. When I was about 20 minutes away from my house (and 30
away from a gas station), my check oil light started to flicker on and
off. Then my car started to shake and bang it was dead.
  I got it towed to a mechanic, who said that the last guy to change
my oil had replaced my drain plug incorrectly. I had my oil changed
only a month ago. Now my motor and radiator is shot. My car only has
100K on it.
  The mechanic says that it is the responsibility of the guys that
changed the oil, and that they owe me a new motor. They say no.

  A: Is it possible to prove responsibility?
  B: What should my course of action be?