Cam belt failure at 83k miles - who's responsible for the repairs?

I own a 1999 Ford Fiesta and a local independent garage has serviced/MoT'd the car regularly from new and we've relied on their judgement as to what should be done. The car's cam belt was replaced by this...

Struggling to remove a timing belt

I have recently changed the harmonic balancer in my Volkswagen Passat 1.8 litre non turbo and had to remove the timing belt from the camshaft pulley - which was fine. I aligned everything to its correct...

When should I change the cam belt on my Audi TT?

Can you tell me when I should replace the cam belt on my Audi TT? The dealership are advising it needs changing now as it is five years old - is this correct?