Seat belt

Why do you need to replace the seat belt? The job is pretty hard and trust me, even Volvo mechanics hate doing this job? So tell me what is going on with the seat belt and I may have a simpler solution then replacing the whole seat belt. And if it sounds like you need a seat belt, I will let you know and tell that you better take it in to have it done at a shop. So let me know what is going on?