If it's the little silver cap inside the unit itself, I don't think there is a TSB for that - it's at your own cost.
They redesigned them later on in-life, and they look totally different now, so you're pretty much forced to buy both if you're concerned about then way your car looks.
Off the top of my head $80 each.
Or, scour ebay etc. for an early model foglight.
Somewhere on this forum there are pics of both kinds of light.