who is right?

[jets]

What you call the acoustic balancer is normally called harmonic balancer & I can't see that being affected by the first mechanic unless it was mechanically damaged. These things have a limited life, maybe 200,000km & fail when the rubber part starts cracking. You need more info from the second mechanic as to why it needs replacing. Maybe he is saying it needed replacing by the first mechanic & he didn't check it.
As far as looking for a refund I would have thought the firm would still be responsible even if the mechanic who did the work has moved on.
That is only my opinion though as I do all my own work & don't get involved in that stuff.

[brad]

Generally speaking, if you get workshop A to do work & then get workshop B to do more work without allowing workshop A to make good then you are out of luck as it becomes a "he said / she said" situation.

Unless of course workshop B is willing to provide documentation proving workshop A was somehow responsible for the problem (good luck with that).

Any warrantable items are connected with the business & not the mechanics that work for the business, so even if staff come & go, the business provides the warranty on workmanship & parts.

[gfh]

The balancer was cracked as shown to me by mechanic 2. But the worst thing discovered was the replacement parts renewed by mechanic 1 failed. Of course he is using the if you came back to us first................... Was told by mechanic 2 that I was extremely lucky not to have dropped a valve. Mechanic 1? would have thought he had a moral obligation........yea I know dreamin.