water

July 2015, it rained for 10 days in Tampa. My Bonneville SSEI filled up with water while sitting in my driveway! I had to have the carpet pulled out and hung to dry and replaced the headliner. The upholstery place blew out all the drain holes and took lots of stuff apart and cleaned leaves out, etc. It has leaked and filled up a couple times since, including last night. They can't figure out where the water is coming in. Can you offer any insights or have you heard of any others with this body having this problem? It has a moon roof, but it has never leaked. The water shows up on the floor of the rear. It's such a nice car, I hate to have this problem!!!