It's a nightmare to get rid of. I saw on a TV programme where you need to bash the stems before putting weed killer on them. No doubt someone on this lovely group will have a good solution for you. Good luck.

You might test the ph of your soil, they prefer an acid soil, if it,s acid, add some lime, this should reduce the numbers,but wont get rid of them altogether, when you see the "spears" they send up this is when they,re full of spores, pull these out as soon as you see them, before they have a chance to open their leaves, you will have to check them on a daily basis, but they should give up the ghost eventually, {might take a year or two just persevere.}