Posted: Yesterday at 08:22
I would use Weedol Rootkill Plus - apply it as per the pack instructions and leave weeds until they have withered and turned brown. That means the weedkiller has gone into the roots too.
However, the ground elder must have spread in there from somewhere - check your boundary fences and sink vertical root barriers
http://www.hy-tex.co.uk/index.php/products/geotextiles/root-barrier-c3 into the ground if the ground elder appears to be coming in from outside of your property.