I wondered about 'snake grass' and looked it up, now I understand, this is what we call 'horsetail', a real pig of a primitive plant. The reason it keeps coming back is that there is a really deep main root, when you spray with weed killer it kills off the shoot , but not the main plant. It does weaken it a bit though, so if you keep at it, hitting every new shoot as it comes, you do get it in the end. One really good idea I saw was cutting the end off a large plastic drink bottle, popping it over the shoot, and spraying in through the neck of the bottle. You won't accidentally spray nearby plants, and you will know which you have and haven't sprayed.
It requires persistence over a long period to eradicate, and you might run into problems if it extends into neighbouring properties, but even then you should be able to control it.