What is eating my chillies and peppers?

Hi, I am growing peppers and chillies in the greenhouse in grow bags and pots and they are being systematically eaten. I have raised the grow bags off the floor as I noticed there were wood lice underneath. I have put plastic rings around each plant and as a last resort sprayed them with a veggie insecticide but they are still getting munched.  . It starts on the leaves first and a couple are now just stalks. Any ideas or help would be greatly appreciated.

Thanks Growster. I haven't seen any slime but will try some pellets. I didnt realise they could climb so high! 

I did once find a monster snail making its stately way across the ceiling in my hallway. They must have fantastic traction