Hi there Allyano,
I'd say that Eircom are correct. Obviously the line is not in current use.. no-one is paying for it right now and it was probably deactivated some time ago. So it has to reactivated, tested etc and Eircom charge for that.
Unless you need a landline for a phone I'd suggest you stick with a mobile and use a wireless ISP for broadband. Good luck.
Dickiesam
PS: It doesn't matter who your eventual phone provider is, the line would still have to be activated etc by Eircom.