seat belt probs

hi all, both drivers and passengers seat belts dont seem to "stop" i.e. if i have a crash im through the screen, there are 2 plastic bits on each side of the mechanism which say do not remove, does this mean they are both u/s and need replacing or can they be fixed, dont want to spend loads im looking to sell the estima soon

Do the seat belts retract? Do they lock up if you come to a sudden stop? Can you post a picture of the plastic bits? What does u/s mean?

Do the seat belts retract? Do they lock up if you come to a sudden stop? Can you post a picture of the plastic bits? What does u/s mean?
seatbelts retract ok, im going to try a sharp stop today, i will post a picture of the sudden stop doesnt work, and U/S mean unserviceable(army term)
cheers