Blocking vents when insulating attic

Hi,
I recently got my attic insulated between the rafters and the attic floored.They brought all of the boards in the rafters down to meet the flooring, sealing the attic off.
The vents in the bedrooms are all in the roof as opposed to the walls. There is very little air circulating in some of the rooms so I took off one of the vents and can see the insulated boards between the rafters. Should the boards should have been installed down this far - to the eaves. Or should they have stopped at the flooring level so that the vents would have direct route to the eaves and, hopefully, fresh air. I am thinking of cutting a route through the boards so that there is a path for the air to the vent and room.
The idea, so the builder claims, with putting the vent on the roof instead of the external wall was to avoide excessive draft. Not sure if this applied when the insulation goes all the way down the rafter, as described above. Hope this makes some sense and would appreciate advice.

The attic space needs ventilation - not only for the rooms vents but also to avoid moisture build up in the roofspace. Otherwise this will cause the roof timbers to rot over time.

thanks for getting back. They left a gap on the cold side of the insulation (50mm) per building regs so I would think that the air can still flow through on this side of the insulation. I'm a bit confused here - when the insulation is at joist/ceiling level the ventilation at the eaves allows cross ventilation in the cold attic space. But when you insulate the pitch the attic effectively becomes part of the heated house - so how is it ventilated?