A few things to check,
Door seals
Blocked plenum (remove wipers and panel for access most urgent job)
sunroof drains
where the sunroof drainpipe goes into bulkhead , this is passenger
footwell side behind panel by door , mine popped out & filled not only passenger front but rear as well , not pretty !!
URGENT check>>>>>plenum if this gets full of water then it will enter the footwell
READ THIS the last two on the right....
http://www.the75andztclub.co.uk/index.php?thepage=howto
Andrew....