Besides - the only 'problem' Zen are suffering from is Buggz and others with exessive usage. Why should other customers pay for their usage.
This solution is good - it reduces the impact they will have (or makes them pay more towards it) whilst not penalising further the rest of the paying customers. As for the 'problems' they had with support, I'd say this proved their price drop worked as they had to recruit new staff. And anyone who's been involved in IT recruitment knows how difficult and time consuming it can be to recruit good staff and train them up.