I'm sorry to read about the problems you've experienced with your Volvo.

If you had owned the car for less than six months, the 2015 Consumer Rights Act would give you strong grounds to argue that the problems were present or developing at the time of sale.

After six months, it falls on the consumer to prove the failure was due to a sudden and unexpected mechanical breakdown. And this is very difficult to do with things like clutches and flywheels.

I imagine the dealer is arguing the failure is caused by excessive wear of the clutch and flywheel. You could counter this with an independent engineer's report, but it will incur further costs and provide no guarantee of a positive outcome.