Toob turned up in our close one day (yes, out of the blue!) and dumped three huge masts in a kind of triangle in very inconvenient places (middle of pavements, top of steps), all of which were an eyesore, and with no need whatsoever for them, as fibre optic cables and other internet services are readily available in our area. Toob have form for this, they have made the local papers several times doing this, and not in a good way.
Our road banded together and complained, together, individually, and repeatedly, to Toob. Our local councillors (Lib Dem, Labour) got involved and objected. So did our MP. Finally Toob removed them.
It's highly unlikely they cause health issues - you won't get anywhere arguing on that front. We objected to the careless way they were dumped, how awful they looked, that they caused access issues, and were not necessary. I don't really care if that's NIMBY or not, and I'm happy that they are gone!
Other roads in the area were not successful. I suspect we were successful due to us all coming together, our persistence, and because all our objections were valid.
Good luck!