Two Door 2004 Golf Location of Rear Airbag/Crash Sensor

[IMK1230]

Hello,
I have the dreaded airbag alarm coming up on dash and friend doing job says the error code is the rear UK near side crash sensor.
This has happened many times now and seems related to folding down and up the rear seats.
Friend wants to replace the sensor but can't seem to locate it as two door car.
Can someone enlighten as to sensors location please or link to picture.
Many thanks in advance IMK

[Crasher]

We need the fault code for the component ID number such as G257.

[IMK1230]

We need the fault code for the component ID number such as G257.

I have been told Code is 01638

[Crasher]

01638 - Crash Sensor Side Airbag; Rear Drivers Side (G256)

Thats the one on the left, HOWEVER I have had instances where this has not been correct for right hand drive, the wiring diagram says it has a blue/red and grey/red wire to it. The sensors are under the back seat on the inner arch panel near the seat belt anchor point.