FCC set up Twitter to give custom alerts, which seemed like a good idea. I have no idea if it still operates or if it works.
My guess is since the new systems came in, it's probably broken. If it's like the text alerts, I can now receive texts to warn me of delays that never happened, or cancelled train warnings some 2-3 hours after I've got home!
I see that EastCoast has a Twitter feed that also gives regular updates, and it must help staff on the ground as it means I could be anywhere on or around the station (or even away from the station) and get alerts as quickly as staff - and EC can relay information to everyone instead of one poor staff member having to shout, or say the same thing over and over.
This is what Twitter is good for (it's a shame it so rarely is!) and FCC did seem to be doing that last December. My next guess is that someone who was given the job to do it has either left or gone on to do other things, or they've forgotten the password to login to their account.
As for the interaction and individual replies/mentions, this is PR gold. All the major companies now use this, so you can moan about problems with your bill, the product you bought, or whatever directly to people who can help and escalate the problem. However angry someone might be, when they get a reply (or a solution) they can quickly calm down.