i have never fixed one of these before,
is a shiny black glas hob with touch sensitive buttons, the problem is you really need to push very hard to gat the buttons to work, is there any adjustment on these or is the panel faulty, i couldnt see a model no. anywhere.
there was a mod for some of these which involved spacers under the control unit pushing it harder into the glass and making it less likely to flex and droop down when hot. Model number will be on the bottom where they are on all hobs. someone removed it maybe?
part number was 762810749 but this fault normally occured after the hob has got hot so you cannot turn the heat or anything off without shutting the power off from the wall, if yours is a bad contact even when cold it may not do the trick, the touch panel is easily removed from underneath I would have a good clean of the underside of the glass and ensure a good contact between the pads and the the glass.