MD Mondeo creaking windscreen

[nicrobell]

My MD Mondeo has just covered about 7k since new and has recently developed an annoying creaking noise that I have determined is from the top area of the windscreen. The noise is easily reproduced by external pressure on the screen. By pushing on the top of the screen from inside the noise stops. Has anybody experienced this issue and what action was taken. The dealer has acknowledged there is a noise but didn't know what it was. I discovered the source of the noise after the dealer had a look. They say they need the car for a week to find the noise. I don't think that's a good idea. Any suggestions are welcome. Maybe a windscreen specialist has a solution.