My Fiat Panda's ('55 plate) passenger's footwell fills with water only after heavy rain. I think the water must be coming in from underneath the car when I drive over puddles. It doesn't seem to be coming in through front heating ducts, windows or doors etc as all these areas are dry. I've taken the car to a main dealer who checked the car and said there were no obvious holes. They also said they would have to take the inside of the car apart to find the leak as they had hadn't heard of this problem before. Maybe I'm being cynical but I'm not sure if they are being totally honest. Obviously I want to try and avoid a hefty bill to locate the leak so I would appreciate some advice.