method 1... trying having someone outside press down on the bonnet to relieve some of the pressure while you pull the release lever
method 2.... the bonnet release cable is an outer sheath with the release cable running inside (same a bicycle brake cable) first spray some WD40 (or similar)into the cable wait awhile then using pliers pull the inner cable outwards grip the outer sheath with another set of pliers if need be but not to tightly if either of these methods work before you shut the bonnet check the that the cable has'nt stretched so may need adjusting to stop it happening again but put some grease/oil/vaseline all over the locking mechanism and work it a few times before closing the bonnet
esrva00
June 2011