What?! you mean it was not diesel in the tank at all?
That was obvious from the first post in the thread.
A ripped rubber coupling for the throttle body would let extra air in, which may result in the engine RPM increasing if extra fuel was delivered as well (depends on type of injection system, many look at throttle angle which wouldn't have changed).
It's very odd how it only showed itself right after filling with fuel though. Given the level of incompetence displayed so far, I wouldn't be at all surprised if the dealers caused the damage whilst removing the throttle bodies, and the high revving was caused by something trivial like a pinched throttle cable. Pure speculation of course and no way of proving it now.