Acanthus, what do I do?

[Rowlers]

Hi all you green fingered ladies out there.
It's Sunday and I'm doing a bit of gardening.
Have 2 big acanthus plants in front garden. They have been much nibbled by slugs and snails and have hardly any leaf left. Flower stems have also gone over now.
The one I have in the back hasn't been touched though. Still lots of lovely green leaves.
What do I do to the 2 in the front? Do I cut them back to the ground and hope they come up next year or leave them alone?
Any advice would be appreciated as I can't find much info in my books here.
TIA

You cut them down in the autumn. They're very persistent plants anyway. I had some in the wrong place, took out original and still seedlings came back! Ooh, I must get out there, too!

Thanks Agy for that. Will get out there and chop them back.