still needing help with allotment troubles!

As you can see i am still having trouble with this allotment!!!

The trouble now is something we call in England (horsetail or mares tail) i know from trying to dig it out it is almost impossible,but didn't know just how difficult!!
On Wednesday i was talking to the grave digger(we park in the cemetery car park)he got talking about the allotments and was horse tail growing there ,i of course said yes,told me he had dug a grave and hit the water table at six foot and that the horses tail was at that depth Like a carpet...the roots that is.As we ....my husband and i were walking away his parting shot was (enjoy your digging)THANKS we replied ...some people really know how to cheer you up!!

so help anyone ,any ideas:shk: