I am delighted with my 2.2 turbo diesel, but over the last couple of months it has developed a noise from the dashboard, it sounds like a drop of water hitting the windscreen (like if you go under trees when it has been raining) me and my wife have pressed and held every piece of plastic and trim we can possibly reach but still can't find it. Originally it was happening just occasionally as I drove along on the flat, but it is getting more frequent and now happens as I drive over bumps as well. Any suggestions gratefully received - its driving me nuts!