Ford Focus Mk1.5 - Leak dilema - WT54

I have an 03 plate Focus which has a pretty severe [rain] water ingress problem. Water is entering far up in the n/s/f passenger footwell (under the dashboard). When I say entering, I really mean it, as the carpets and under felt are soaked along the nearside.

I replaced the pollen filter scuttle panel and seal, and sealed it up with sealant (I should add that we have another Focus which I have sealed in this way which is dry as a bone inside). The leak continued. I have checked door cards and door seals (well, friend has), all were fine.

I lifted the carpets to dry them out and possibly find the source of the leak in May this year, as the damp smell was annoying me. As soon as it raine again, water was back.

I think that the windscreen has been replaced recently (I bought the car in Feb this year), and I'm starting to wonder if the leak is round the screen. I've read on the internet of replacement windscreens not being sealed properly - which is worrying, as I think they are part of the structure on a Focus? The screen appears not to be a geuine Ford item, as the Ford badge is not there, instead there is another makers name and a small white sticker with what might be someone's initials on. It soon became apparent that the people I got the car from weren't too keen on doing any maintenence, so may have used a dodgy backstreet glass fitter.

Can anyone suggest a way forward with this? I'm disabled, and would really like to trade in this car soon for a C-Max, which would be easier for me to get in and out of. No dealer would touch this Focus with soggy, smelly carpets, what should I do?

Many thanks,

David