well i'm not too sure its snapped now as i went for the pliers option i think its just not been used in that long that they've seized shut and arent releasing. i did try looking last night but it was getting dark so i'll try the latter option in a moment. any other suggestions?
Get someone to pull the lever, quite hard and at the same time, wriggle the bonnet and thump it with the bottom of your fist, without damaging it of course!