If the cable is not actually snapped you might try this.
Drive the front end up onto a kerb..our school carpark did nicely. Roll back off the kerb while pulling on the lever. Voila! My bonnet popped and I took the opportunity to clean (wd40 and 3-in-1),sand smooth and grease up any dodgy bits before putting the bonnet down again. Haven't tried opening again but I am confident! :-)
Terry McGeary
May 2010