You are joking aren't you?
How can you say you are short of controllers because of productivity? You are a bloody service industry! You have to have people to provide the service to get the productivity surely?
For example, why would I as an airline / individual pay you IFR navcharges if you tell me it is TIBA?!
The cost of all that lost revenue makes a mockery of your perceived 'productivity' bonuses doesn't it?
As far as I am concerned get rid of the bloody managers and put someone in the ATC seat.
No bugger really knows what to do when this happens. Is it going to take a mid-air to wake you all up?