I was doing some work on the front seat of my T5 today as the side of the cushion had worn through { 306000 kms ] of getting in and out will wear out eventually . Any way while I had the seat out I lifted up the rubber mat to find some water sitting in the recess in the floor , there is a cut out in the mat for some wires to come out off , these wires go into a junction box directly above the cut out . This is where the main connector for central locking is as well and would explain why the locks have failed from time to time , last time my locks played up I removed the plug and found a lovely green growth around the pins . I used a special electrical cleaner from Jaycar to neutralise the growth and then spray the pins with a special protective coating , it seems that as the floor slopes from under the dash downwards towards the seat any water will end up under the seat which then causes condensation to rise up into the junction box . This also explains why my subwoofer amp has now failed as it also sits under the seat above the same spot , worthwhile checking this junction box if your locks are erratic and also the water leak but that will be another job for another day for me . New amp fitted and now more bang for my buck !!