had an alternator fail earlier in the week, nothing amazing there but it was how it failed that may be of interest.
the above manufacturers have a small clutch arrangement in the pulley to reduce wear and tear on the belt tensioner as the alternator’s centripetal force can have an adverse effect (apparently).
anyhow this clutch soon runs dry and reduces the effectiveness, eventually seizing and falling to the bottom of the engine bay like mine did on monday.
a bit of internet trawling and the best price for an alternator was 300-400 quid plus fitting!
I found partco on broadfield road do a reconditioned unit for 190. fitting was a bit of a ball ache but done in 40 minutes by myself on the roadside, hate to think what gilders would charge!
anyway it may be something to try and check and if your car sounds like its got a squeeking fanbelt it may be the alternator pulley instead.

That happened to mine a few weeks ago, taking the damped tensioner with it.

You won’t want to hear but the clutch is a replaceable part, about £50 including the tool to change it from any decent motor factors, it’s rare that the alternator itself would have been damaged.

Although a lot of the tools are designed so you can change the pulley in-situ if you’ve got the STW car of choice, 1.9tdi Octavia, the chassis leg gets in the way and you have to drop the aircon punp and get the alternator out from below. Makes it about a 2 or 3 hour job.