What's wrong with my Audi A3?

We have a 2008 Audi A3 2.0 TDi which has covered 73,000 miles and is driven twice a week (90 miles on a motorway) with a couple of urban miles at either end. We have had it serviced by Audi all its life and it is in a good running condition. However, at last week's MoT and service, we were told that it needs some parts replaced at a cost of around £2500. No lights have ever illuminated and we've had no indication of anything wrong. What could it be? And should we sell it before anything else expensive occurs?
It is overdue a timing belt and waterpump change. But that should not be more than £500-£600. They might mean dual mass flywheel and clutch, but that should not be more than £1300.
Answered by Honest John on

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