difficult to see how to ruin oil pressure changing a belt.difficult to come up with a way to do it deliberatly.how did it fail?is it siezed?did you drive it with the light on?understand you'r position but mechanics get this every week.accusations of shoddy work and no doubt some are true.but to create your fault would require the engine to be run without oil.why would anyone do that and how would you know how long to run it to do just enough damage and still run enough for you to drive away.sorry but i think not this time.
caine
August 2008