2004 BMW 530i Water Intrusion

I have an 04 530i and live in LA, California. we have had some rain storms last week and the passenger side front and back have a significant amount of water in the footwell areas. we took it to the BMW dealer to have it looked at and they said they can not find where this amount of water could have gotten in. They said they were able to confirm a small leak in the sunroof which may require a seal. They have checked the door shields and winsheild and all have checked out good. Bottom line is they want over $1k to "repair" the roof with no assurances it will stop the water intrusion. Any help from you would be appreciated.

Thanks