Terrain Collider update c#

Hi all,

I'm displacing a Terrain object using image(s) at runtime.

The problem I'm running into is that the terrain collider isn't getting updating (I realised that I need to do it manually in the c#). There used to be a way to do it quite simply using the old version of the Terrain system, but now I'm at a complete loss as to how to do it and the docs have be completely baffled tbh.

Would anyone have any idea how to go about it?

Thanks Spud