when this happened to me it was the cables to the bonnet latches had rusted/worn/covers split,, picked up good condition latches and cables from a low mileage car at breakers,,, its not a hard job to replace them , just a few bolts and some wood to wedge up the upper panel to allow the latches to be pulled out.
http://www.the75andztclub.co.uk/foru...0&d=1469206035
http://www.the75andztclub.co.uk/foru...3&d=1469206109