Major leak somewhere

[kilvi00]

Hi all, I have a BMW X5 58 plate and about a week ago I noticed after heavy rain that there was water dripping from my overhead light where the sunroof controls are, I read that the drain holes in the panoramic sunroof could be blocked so I cleaned them out with compressed air, this seemed to work for a while but then I noticed a damp smell in the car and discovered that all my carpets were soaked and that there was water dripping from the lights above the doors in the back and again from the overhead light.
I tried cleaning the drain holes again by putting some strimmer cord down but it only goes about 6 inch.
I have spoken to a couple of mechanics who have said that they think there are more than just these two drain holes so I was wondering if anyone knew where they all were and anyone have any idea of cost to have this problem sorted.

thank you