Paul, getting the hairpin right is something that took me a long time to get anywhere near right, and I'm still trying to improve as it seems there is still time to be gained through that section.
I would guess that like me you are making the mistake of going in too deep and too fast on a setup that( as has already been said) bottoms out in the dip.
This leaves you with a car that is more or less a missile as you hit the uphill right hander , and propels you either a) into the barrier on the outside
or
b) you miss the barrier ( just) and slide wildly across the grass??.
The loss of any directional control is almost certainly because you are "bottoming out" in the dip and yes, GPL does punish you for doing that
Try this approach ( in private where no-one will laugh when you get it wrong)
Then adapt it to suit your own style.
After you come over the crest at the top of the hill approaching the dip, give a squirt on the gas, not necessarily flooring the throttle pedal, but enough to settle the car .
As you pass the section of armco on your right, brake hard, but get off the brakes and probably into 2nd gear before you hit the bottom of the dip. By doing that you will allow the car to regain full ride height before the springs are compressed again by the physics of GPL by the dip.(If you still seem to lose all control at this point then go back and either raise the ride height or stiffen the springs a little, and try again.)
With any luck you will now be hugging the inside kerb and gently accelerating up the incline, aiming for the outside of the track just beyond the end of the armco.
Personally I drop into 1st gear as soon as I have crested that short rise and settle the car for the hairpin, but this might depend on your selected gear ratios and you might wish to stay in 2nd. Practice will tell you from this point what is the best line through this tight corner. I try and take a late(ish) apex
but avoid that kerb on the inside, because any contact with that will ruin your corner!!The important thing here is not your ENTRY speed into the hairpin, but a clean and smooth EXIT onto the straight where you get the power down under control and are not fighting a bar of soap with springs fitted.
Hope this helps you a little to understand what is going on around there. Basically there are so many elements to this short section of track that you will need to practice this a few times( about 500 should do it
) to get a feel for what is happening. When you do get it sort of right you will wonder why it was such a problem before.................honest lol