Yeh, had the same problem. I thought I would buy some bright fog lights and went for the highest wattage I could find. They ran ok a for a few days but then one fog light housing melted. I guess oer the few times I had been running them the bulbs had slowly heated up the plastic to the point they wouldn't hold any more and then just collapsed and melted.
Lesson learnt - Stick to correct wattage bulbs.