e53 water leak

[switchman]

My '06 e53 is at the dealer since 12/14 for water leak. Water collects in rear padded compartment behind wheel well next to electronics, left side and below fuse block, right side.
Water does not always appear until vehicle is driven, so its collecting somewhere else before it flows down. its been at the dealer since 12/14 and they are stumped after they have replaced the sunroof drain tube and perimeter seal. They found collapsed LF drain tube after it leaked in driver side which had not happened to me. Dealer had performed sib 540606 & 540409 already but when i picked up the vehicle last Saturday, we found water again in left rear compartment. Needless to say, my truck is still with dealer. I jokingly said to them i'd be more than happy to keep the e70 loaner, its a '09 with barely 14k miles.

So, does anyone have this problem ? I've researched this site and found writeups that are a little bit different from mine as water was found collecting in spare wheel compartment but not above it ?

Thanks in advance for any advice.