I don't think they succumb to any weedkiller Peppie. I had them, lots of them in an uncultivated garden of a new house we had a few years ago, and the only sure way to get rid is to hoe them off EVERY time you see one. Eventually they give up the ghost, and after 4 or 5 years, they stopped coming.

thanks i moved into this house 3 year ago there was no garden sawn down trees at the font and all top soil at the back was taken away right down to the clay but its slowly getting there

They are certainly susceptible to Glyphosate, which is a systemic herbicide.....there have been lots of control studies for exactly this problem in fact.

The issue you will have in using any weedkiller on Equisetum is that the surface area of the plant is so fine and difficult to wet properly, plus it is relatively small in comparison to the root system. It's a question of repeated applications to get as much of the herbicide onto the growth as possible and gradually weaken the whole system of the plants.

thanks been using that every time a new shoot shows shame they were'nt edible we could feed the world

I remember researching this for hours on the Internet and eventually finding a website in America which had some incredibly toxic poisons which could actually get rid of this weed. Not available to the public of course, and not to be recommended on gardens we use every day.
As Ilex suggests, if you bruise the foliage first (easier said than done) before spraying with glyphosate then the result will be better. Maybe adding washing up liquid to the mixture would help break down the waxy coating on the plant.
Although it's a nightmare in the middle of a flower bed, I find it no problem with vegetable beds as the frequent cultivation keeps it under control.
My control method in the flower beds is to put up with until around this time of year, and then go through the beds with sharp hand shears snipping each long shoot out and removing it. Although it will come back of course, I find doing it later rather than earlier sets it back more and where I did this ten days ago, there's no sign of regrowth yet. If you do it two or three times a summer, you can at least get a reasonably good cosmetic aspect to your flower garden.
You can also soak the cut shoots of horsetail and make a 'tea' which is a good fungicidal spray as the silica it contains deters mildew and blight etc.

good one i might try it thanks every one