We could use a little more info on your problem -- where exactly is the leak, at the pump or at the front of the car?
Did you have noise or hard steering before the leak?
What mechanic has worked on your car - dealer, Porsche specialty independent, or other type?
Did they show you the failed seal -- is it red plastic or black rubber?
There are several seals on the pump and there are 2 reservoirs.
Heat causes the red plastic clamp/seal to melt and leak.
But, high pressure from a failed rack and pinion unit could blowout other seals on the connecting pipes and/or the pump.
Since heat doesn't seem to be the cause then the rack and pinion unit or a valve may be the real cause.
There are few people that have had rack failures, and they may have better info for you. I have only delt with the red plastic clip failure.