I had a stuck bonnet recently (should have seen it coming after I had trouble getting it to catch) and couldn't work out from the advice how you were supposed to reach under the bonnet to release it (the catch is a fair way back and the grill gaps narrow) so I called the AA. After 40 mins of me pulling red lever and AA man prodding and wriggling around bonnet the AA man gave up but suggested a particular garage.
The garage managed to use a long tipped screwdriver to remove the front grill screws (they turned out not to be rusty, which was AA man's fear) and somehow angled the grill out with the bonnet still down. He then unscrewed the catch assembly unit and removed the whole lot. Degreased unit, regreased it and it's been fine so far since.