Hi Folks
I've just discovered that the passenger side inertia seat belt is being eaten alive by the rough edges around the hole through which it emerges at the rear of the car

. I know this is not uncommon but also that factory replacements are ridiculously dear.
Can anyone advise me if their replacement is a DIY task and a suitable source of new belts?
Many thanks in anticipation (the car is a 2004 Roadster)
Roady