X5 E70 Rear Fog Light

[Kudos]

I've had one of these units go faulty, so currently looking a replacement. It started to flicker a while back, now the entire unit is out - brings up a fault every time I switch car on - "rear right fog light failure".

Does anyone know if this is a case of replacing entire unit or simply just a bulb?

I had assumed it was a unit, but looking at a couple of parts stores it might just be a bulb, but keen to know as I'm not the most technically minded...

TIA