Yes, they are likely to do this. The employees have a tendancy to do this given that they own a big chunk of the company.
What will happen at worst is that you get left till last for repairs if theres a number of lines down in the same incident.
Question is, how often is this likely to be a problem. Secondly, even when it is, are you happy to be held to ransom (by staying with eircon, your encouraging them to keep doing this)?
By the way, BT ar'nt without their problems (search this forum ref. BT billing).