Seat belts problem

Hi everyone,
Much to my horror after a short drive this afternoon I discovered both inertia seat belts are not working. The passenger side does not even retract with the drivers not stopping as it should when tugged quickly. Is there a repair company anyone could recommend? Or, just bite the bullet and replace with aftermarket (Nothing from China) that anyone has personal purchase and use of their replacement belts.
I would rather go on recommendations from personal experience. I also imagine the fabric of the belt itself could also be compromised.
Many thanks in advance for an suggestions.
Best regards,
mine don't stop when quickly tugged either. both retract though so pass MOT test! currently looking to replace mine and install rear at same time. aware theres a company will use your (Rover) buckles.mounts etc and just replace belt(s) but cannot recall whom that was . not cheap as buying new ( china?) of course. good luck.