Not so road worthy and we don’t mind

Hi there,

I serviced my car in October and picked up some defects which the manager agreed to addressed and they were handled well. However one of the defects, the headlight was not fixed. I was assured that they would order and arrange to fit it in the car however after numerous efforts it still hasn’t been fixed. I keep making contact with the mechanic who was assigned to service the car and fix the headlight, unfortunately he’s been avoiding me and not helpful at all. Who will be liable if I replace the headlight since I had already paid and who becomes liable should I be fined for a headlight not working?