I have seen these small bits and pieces of sponges in my car once when I was cleaning the car's carpet. The broken pieces of sponges were not actually inside the air-cond vents but beneath the driver's seat. At first I thought the sponges came from the fabric seats, suspecting the seats had a tear and the sponges leaked out or something. But after second thought, the bits and pieces of sponges may have come out from the air-cond vents in my car. If not the main vents at the top, maybe the vents located beneath, near the legs. I didn't bother to pursue to the matter further as it is a small problem to me. After I cleaned up the sponge beneath the seat, I don't see anymore sponges. There are more "problems" with my car that I need to get them sorted out soon in my next appointment.

In your case, you should highlight your case and let them check and fix the problem.

The plastic bery lousy, but the whole thing can change not expensive also. Whole thing fall off? If the screw area broken u have tough luck, if is the switch broken, still ok can glue back but i see the plastic not good if use a few times broke again. If me i just change new. But from shopee cheap cheap only. Terus buy led version, not whole car lit up so bright at night lol