For the first 2 day they said they detects NO parasitic draws at all and they were baffled too on why car was draining overnight. Computer shows no errors either. Then they told me they were able to isolate the issue to the Window Switch ( No sure how they figured that out ??). They first unplugged the old switch and plugged back in and the battery stopped draining. They asked me if I want to replace the switch to have a peace of mind that it won't get stuck again. I did since this issue left me stranded twice , cost of the new switch ( $220 !) ... after they replaced they kept it one more night just to make sure everything is fine.
I can't believe it took them 4 days. Finding a simple parasitic like that is not rocket science.