Does anyone have any experience with replacing oil pressure regulator on Octavia Mkiii 1.6 TDI?

I’ve actually tried removing, but have snapped the body off. I took it to friends garage this afternoon and they too also struggled to remove remaining bit stuck in engine. The insert would just not budge. I’m in some serious trouble any help guidance really appreciated!

Maybe a grub screw that locks into those recesses on the shiney bit of the new one, so at right angles to the main body

I think the grooves in the plunger will be oil galleries.

All sorted. Bumper off, radiator and AC removed, allowing full access. Drilled, tapped and removed with bolt and slide hammer. Expensive fix but these things happen. My observation is that the aluminium body oxidised and reacted with engine casting to seize. After replacing sensor, at least my ACC now works, which was the reason replacing in first instance.