how to stop my renault grand espace passenger footwell filling with water,?

i have water swimming in the passenger footwell, and have checked all seals around doors, windowscreen etc and they are fine. my heater is working fine and still getting hot, so matrix appears to be ok. all levels in engine, radiator, washwipe ect fine, but rainwater getting in to passenger footwell. all rest of floor drivers and rear etc fine, so where is the water coming from? the fuse box is located in the passenger footwell so you can imagine the trouble this causes when it rains, please can anybody help ?