I wish people would post back to the original thread and let everyone know what happened. IE what it turned out to be and how they fixed it and if the issue has gone away.
This would be super useful for ALL of us that own these cars where this seems to be a big issue.
Pushing this lever upwards opens the three clips marked, pushing it down moves them back inwards to lock the bulb in place.
This is left-hand side (passenger) side, I haven't looked at drivers side since it involves wrestling the wheelarch liner out.