Backup camera on the fritz

[Yokosuka X-1 Driver]

I have a 2011 X-1 right hand drive. The backup camera has gone intermittent recently and I have been told that it may be the backup camera control unit. I've searched for the unit but can't find it, does anyone know where it is located? It's not under either of the side cubbies. I've taken the car to BMW here in Yokosuka but since the previous owner replaced the rear hatch camera with an aftermarket model, they won't work on it.