Slide the passenger seat all the way forward, open the back door and remove the the carpet panel below the seat which is kept in place with velcro. Remove the unit by undoing the two plastic 10mm nuts located either side of it and If the unit is or has been wet and the terminals damaged then that could cause the central locking to bug out.
Try ebay for answers. For a couple of quid some people claim they can send you a fix for this. Hope that helps.
Bashir Shah, October 2006
