That's the general idea - they dont want you to find them. They dont want you to e-mail and refuse to give out an e-mail address. They closed customer facing office's.
I'm not sure but I think a third party looks after returns etc.
Crag Ave is just the warehouse, one of the storemen might be responsible for testing the returns, repackaging them and restocking them but I doubt very much that they deal with the public hence the lack of contact details.
If you are still stuck on Monday I will try to find out for you as I have no way of accessing the staff directory at the weekend.
I have certainly not seen any signs for an Eircom office in the industrial estate, yet I have seen the odd Eircom Van going up and down. So I would agree with MBO5 that it might just be a warehouse, hence no contact numbers etc.
Turn into Crag Avenue from Station Road , go all the way to the end , Eircom Warehouse is the last entrance on the right , Impossible to miss. Dozens of Eircom vehicles in the yard.