I emailed about 15 TDs a while back. All my local constituency guys, and all the parties'/groups' representativse on the area I was talking about. About a third of them replied. Four of them followed up again, three putting questions to the government and sending me the response. I emailed those four with an update on the situation last week (things did definitely change, it just took a long time.) Two of them responded back. One of them was the assistant saying thanks and saying there were still issues with the situation and they'd be looking at it further. One of them was the assistant saying they'd be showing my thanks directly to the minister. As in the literal email I sent rather than just doing the work for him and getting him to approve it.
So, over a number of years, from about 15 TDs, two of them/their staff kept up with the whole thing. And it wasn't very complex, but something needed.
The two TDs were Mick Barry, who I disagree with a lot. And Michael McGrath, who I disagree with on a lot social issues but is very capable when it comes to finance.
And, to point out, before anyone says, "TDs shouldn't be concerned with local or personal issues," this was something about national policy. And like I said, things were changed over the course of two Dáils. (And the issue was relevant to this thread.)