Dinosaurs liked horsetail! That is why it is so hard to get rid of, it is one of the oldest plants on earth, and will not take much notice of us johnny come lately humans efforts to get rid of it. As I have mentioned before, in this mining area, the distinctive black 'liquorice string' roots were noted meters down the pits. You can keep cutting its head off, not even horesetail likes that treatment too long.
We had an allotment that we had to abandon eventually as the infestation of horesetail and the solidly matted roots were just impossibe to remove.
Whatever you do, DO NOT rotovate or anything like that - each tiny bit of plant will root and form a new plant - probaby what made our allotment quite so badly infested.