before you go legal, I would try talking to them. Just tease out what the issue is. If its the quad, maybe you might have to forego that just to keep the peace? If its all of it, ie dust, noise, maybe they dont like the look of the track?
I have seen cases where people get so annoyed common sense goes out the window. So they will spend €6k on legal advice and letters, only to get nowhere.
If your thicked skinned, let them take it to you. Until your asked to attend court, its all just words.
if you own the land, the cow track is on your land; I cant see them having much of a legal case. But there are cow tracks, and theres cow tracks beneath a foot of muck.