ah Physics material on the walls,. .that would have been a good idea :P.
I also should have put a "feet" collider on the Zombies,.. but in the end I left in the ability to shimmy up walls, as it was fun :P.
Have to make a choice moving forwards though, wether to leave it in and make it more a feature,.. or fix that and level design fully without it.
Thanks for playing and the feedback!
Will indeed be rating in return all those who comment/rate mine at the front of the queue :) (just might take me a couple of days to get through with work :P)