Hey gang while searching on the net I found this info on another forum about T5 Central Locking & the Rear Doors.
I have been just informed by a guy who claims to work for VW that there is a problem with the locking system on the rear door of the Transporter T5.
If the key fob lock button is pressed once, then all doors will deadlock, if pressed twice, then the deadlock will be deactivated as will the interior security (If fitted) This is correct operation. It has been found that in some cases when the button is pressed twice the rear door will be unlocked, leaving your tools open to any passing scrote who wants a tenner for his next bag of crack.
Check your vans out guys, I did and have found that since I have owned the vehicle my tools have been at risk. Off to insert a large garden gnome into my local VW service manager, VW are aware of the problem, but are not letting on.